diff --git a/src/components/brand/BrandTabMedia.tsx b/src/components/brand/BrandTabMedia.tsx
index 8abd210..88b2fa5 100644
--- a/src/components/brand/BrandTabMedia.tsx
+++ b/src/components/brand/BrandTabMedia.tsx
@@ -131,9 +131,16 @@ export const BrandTabMedia: React.FC<BrandTabMediaProps> = ({ designMD, handleDe
               compact
               accept="audio/*"
               label="Subir audio"
-              onFiles={(files) => {
-                const url = URL.createObjectURL(files[0]);
-                handleDesignChange('brandAudioUrl', url);
+              onFiles={async (files) => {
+                const formData = new FormData();
+                formData.append('file', files[0]);
+                try {
+                  const res = await fetch('/api/upload', { method: 'POST', body: formData });
+                  const data = await res.json();
+                  if (data.url) handleDesignChange('brandAudioUrl', data.url);
+                } catch (err) {
+                  console.error('Audio upload failed:', err);
+                }
               }}
             />
           </div>
@@ -231,9 +238,16 @@ const VideoUploadSimple: React.FC<{
             compact
             accept="video/*"
             label="Subir archivo"
-            onFiles={(files) => {
-              const url = URL.createObjectURL(files[0]);
-              onUrlChange(url);
+            onFiles={async (files) => {
+              const formData = new FormData();
+              formData.append('file', files[0]);
+              try {
+                const res = await fetch('/api/upload', { method: 'POST', body: formData });
+                const data = await res.json();
+                if (data.url) onUrlChange(data.url);
+              } catch (err) {
+                console.error('Video upload failed:', err);
+              }
             }}
           />
         </div>
diff --git a/src/components/express/ExpressEditor.tsx b/src/components/express/ExpressEditor.tsx
index 9cafde5..e4e30d6 100644
--- a/src/components/express/ExpressEditor.tsx
+++ b/src/components/express/ExpressEditor.tsx
@@ -8,6 +8,7 @@ import { StoryboardView } from './StoryboardView';
 import { SceneFieldEditor } from './SceneFieldEditor';
 import { ExpressStylePanel } from './ExpressStylePanel';
 import { compileExpressToTimeline, getAspectDimensions, getTemplateDuration } from '../../utils/expressCompiler';
+import { useVideoDurations } from '../../hooks/useVideoDurations';
 
 interface ExpressEditorProps {
   designMD: DesignMD;
@@ -62,13 +63,16 @@ export const ExpressEditor: React.FC<ExpressEditorProps> = ({
     setFieldData(prev => ({ ...prev, [fieldId]: value }));
   }, []);
 
+  // Probe actual video durations for form-sourced scenes
+  const videoDurations = useVideoDurations(selectedTemplate, fieldData);
+
   // Compile template to timeline
   const compiled = useMemo(() => {
     if (!selectedTemplate) return null;
-    return compileExpressToTimeline(selectedTemplate, fieldData, designMD, company);
-  }, [selectedTemplate, fieldData, designMD, company]);
+    return compileExpressToTimeline(selectedTemplate, fieldData, designMD, company, videoDurations);
+  }, [selectedTemplate, fieldData, designMD, company, videoDurations]);
 
-  const totalDuration = selectedTemplate ? getTemplateDuration(selectedTemplate) : 0;
+  const totalDuration = selectedTemplate ? getTemplateDuration(selectedTemplate, videoDurations) : 0;
   const fps = 30;
   const totalFrames = Math.max(30, totalDuration * fps);
 
diff --git a/src/components/express/SceneFieldEditor.tsx b/src/components/express/SceneFieldEditor.tsx
index 2a712d9..d52a3cd 100644
--- a/src/components/express/SceneFieldEditor.tsx
+++ b/src/components/express/SceneFieldEditor.tsx
@@ -178,11 +178,18 @@ export const SceneFieldEditor: React.FC<SceneFieldEditorProps> = ({
                     type="file"
                     accept="image/*,video/*"
                     className="hidden"
-                    onChange={(e) => {
+                    onChange={async (e) => {
                       const file = e.target.files?.[0];
                       if (file) {
-                        const url = URL.createObjectURL(file);
-                        onFieldChange(field.id, url);
+                        const formData = new FormData();
+                        formData.append('file', file);
+                        try {
+                          const res = await fetch('/api/upload', { method: 'POST', body: formData });
+                          const data = await res.json();
+                          if (data.url) onFieldChange(field.id, data.url);
+                        } catch (err) {
+                          console.error('Media upload failed:', err);
+                        }
                       }
                     }}
                   />
diff --git a/src/components/shared/TemplateFieldInput.tsx b/src/components/shared/TemplateFieldInput.tsx
index d12d356..d146c34 100644
--- a/src/components/shared/TemplateFieldInput.tsx
+++ b/src/components/shared/TemplateFieldInput.tsx
@@ -169,11 +169,18 @@ export const TemplateFieldInput: React.FC<TemplateFieldInputProps> = ({
               type="file"
               accept={isVideoField ? 'video/*' : 'image/*'}
               className="hidden"
-              onChange={(e) => {
+              onChange={async (e) => {
                 const file = e.target.files?.[0];
                 if (file) {
-                  const url = URL.createObjectURL(file);
-                  onChange(url);
+                  const formData = new FormData();
+                  formData.append('file', file);
+                  try {
+                    const res = await fetch('/api/upload', { method: 'POST', body: formData });
+                    const data = await res.json();
+                    if (data.url) onChange(data.url);
+                  } catch (err) {
+                    console.error('Media upload failed:', err);
+                  }
                 }
               }}
             />
diff --git a/src/electron/main.ts b/src/electron/main.ts
index 71da5d4..11489d2 100644
--- a/src/electron/main.ts
+++ b/src/electron/main.ts
@@ -269,8 +269,15 @@ app.whenReady().then(async () => {
     return;
   }
 
-  // 4. Set BRADLY_SERVE_URL for the renderer to find the app
-  process.env.BRADLY_SERVE_URL = `http://127.0.0.1:${expressPort}`;
+  // 4. Set BRADLY_SERVE_URL for the headless renderer (Puppeteer)
+  if (process.env.NODE_ENV === 'development') {
+    // In dev, the React app is served by electron-vite's Vite dev server
+    const rendererUrl = process.env.ELECTRON_RENDERER_URL || 'http://localhost:5173';
+    process.env.BRADLY_SERVE_URL = rendererUrl;
+  } else {
+    // In prod, Express serves both API and static renderer files
+    process.env.BRADLY_SERVE_URL = `http://127.0.0.1:${expressPort}`;
+  }
 
   // 5. Create the main window
   createWindow();
diff --git a/src/engine/components/MediaAudio.tsx b/src/engine/components/MediaAudio.tsx
index 867af03..25c4e6a 100644
--- a/src/engine/components/MediaAudio.tsx
+++ b/src/engine/components/MediaAudio.tsx
@@ -3,6 +3,9 @@
  *
  * An <audio> element that syncs to the player's current frame.
  * Supports volume as a per-frame callback function.
+ *
+ * Key design: During playback, let the browser handle audio naturally
+ * and only seek when drift exceeds a threshold. This prevents audio glitching.
  */
 import React, { useRef, useEffect } from 'react';
 import { useCurrentFrame } from '../player/useCurrentFrame';
@@ -17,6 +20,11 @@ interface AudioProps {
   endAt?: number; // frame
 }
 
+/** Maximum drift (in seconds) before we force a seek during playback */
+const DRIFT_THRESHOLD_PLAYING = 0.25;
+/** Maximum drift when paused/seeking */
+const DRIFT_THRESHOLD_PAUSED = 0.05;
+
 export const Audio: React.FC<AudioProps> = ({
   src,
   volume: volumeProp,
@@ -28,31 +36,49 @@ export const Audio: React.FC<AudioProps> = ({
   const { fps } = useVideoConfig();
   const { playing } = usePlayerState();
   const audioRef = useRef<HTMLAudioElement>(null);
+  const wasPlayingRef = useRef(false);
 
   // Compute the audio's local time
   const audioFrame = frame + startFrom;
   const targetTime = audioFrame / fps;
 
-  // Sync time
+  // Sync time — different strategies for playing vs paused
   useEffect(() => {
     const audio = audioRef.current;
     if (!audio) return;
 
-    if (Math.abs(audio.currentTime - targetTime) > 0.1) {
-      audio.currentTime = targetTime;
-    }
-  }, [targetTime]);
+    const drift = Math.abs(audio.currentTime - targetTime);
 
-  // Sync play/pause
+    if (playing) {
+      // During playback: only seek if drift is significant
+      if (drift > DRIFT_THRESHOLD_PLAYING) {
+        audio.currentTime = targetTime;
+      }
+    } else {
+      // When paused: sync precisely
+      if (drift > DRIFT_THRESHOLD_PAUSED) {
+        audio.currentTime = targetTime;
+      }
+    }
+  }, [targetTime, playing]);
+
+  // Sync play/pause state
   useEffect(() => {
     const audio = audioRef.current;
     if (!audio) return;
 
     if (playing) {
+      // When starting playback, sync time first then play
+      if (!wasPlayingRef.current) {
+        audio.currentTime = targetTime;
+      }
       audio.play().catch(() => {});
     } else {
       audio.pause();
+      audio.currentTime = targetTime;
     }
+
+    wasPlayingRef.current = playing;
   }, [playing]);
 
   // Set playback rate
diff --git a/src/engine/components/MediaVideo.tsx b/src/engine/components/MediaVideo.tsx
index b93b9c3..3156072 100644
--- a/src/engine/components/MediaVideo.tsx
+++ b/src/engine/components/MediaVideo.tsx
@@ -8,6 +8,10 @@
  * - Playback rate
  * - Trim (startFrom / endAt in frames)
  * - Play/pause state from player context
+ *
+ * Key design: During playback, let the browser handle audio/video naturally
+ * and only seek when drift exceeds a threshold. This prevents audio glitching
+ * caused by constantly setting currentTime on every frame.
  */
 import React, { useRef, useEffect } from 'react';
 import { useCurrentFrame } from '../player/useCurrentFrame';
@@ -24,6 +28,11 @@ interface VideoProps extends Omit<React.VideoHTMLAttributes<HTMLVideoElement>, '
   onError?: (e: React.SyntheticEvent<HTMLVideoElement>) => void;
 }
 
+/** Maximum drift (in seconds) before we force a seek during playback */
+const DRIFT_THRESHOLD_PLAYING = 0.25;
+/** Maximum drift when paused/seeking — needs to be frame-accurate */
+const DRIFT_THRESHOLD_PAUSED = 0.05;
+
 export const Video: React.FC<VideoProps> = ({
   src,
   volume: volumeProp,
@@ -39,34 +48,51 @@ export const Video: React.FC<VideoProps> = ({
   const { fps } = useVideoConfig();
   const { playing } = usePlayerState();
   const videoRef = useRef<HTMLVideoElement>(null);
-  const lastSyncRef = useRef<number>(-1);
+  const wasPlayingRef = useRef(false);
 
   // Compute the video's local time
   const videoFrame = frame + startFrom;
   const targetTime = videoFrame / fps;
 
-  // Sync time
+  // Sync time — different strategies for playing vs paused
   useEffect(() => {
     const video = videoRef.current;
     if (!video) return;
 
-    // Only seek if significantly out of sync (>50ms) or if frame changed significantly
-    if (Math.abs(video.currentTime - targetTime) > 0.05 || lastSyncRef.current !== frame) {
-      video.currentTime = targetTime;
-      lastSyncRef.current = frame;
-    }
-  }, [targetTime, frame]);
+    const drift = Math.abs(video.currentTime - targetTime);
 
-  // Sync play/pause
+    if (playing) {
+      // During playback: only seek if drift is significant
+      // This lets the browser's audio decoder run smoothly
+      if (drift > DRIFT_THRESHOLD_PLAYING) {
+        video.currentTime = targetTime;
+      }
+    } else {
+      // When paused or seeking: sync precisely for scrubbing accuracy
+      if (drift > DRIFT_THRESHOLD_PAUSED) {
+        video.currentTime = targetTime;
+      }
+    }
+  }, [targetTime, playing]);
+
+  // Sync play/pause state
   useEffect(() => {
     const video = videoRef.current;
     if (!video) return;
 
     if (playing) {
+      // When starting playback, sync time first then play
+      if (!wasPlayingRef.current) {
+        video.currentTime = targetTime;
+      }
       video.play().catch(() => {});
     } else {
       video.pause();
+      // When pausing, sync to exact frame
+      video.currentTime = targetTime;
     }
+
+    wasPlayingRef.current = playing;
   }, [playing]);
 
   // Set playback rate
diff --git a/src/hooks/useVideoDurations.ts b/src/hooks/useVideoDurations.ts
new file mode 100644
index 0000000..2b68685
--- /dev/null
+++ b/src/hooks/useVideoDurations.ts
@@ -0,0 +1,66 @@
+import { useState, useEffect } from 'react';
+import { ExpressTemplate } from '../types';
+
+/**
+ * useVideoDurations — Probes actual video durations for form-sourced scenes.
+ *
+ * When a user uploads a video to a form field, this hook creates a temporary
+ * <video> element to read its metadata and returns the actual duration in seconds.
+ *
+ * Returns a map of sceneId → duration (seconds) for scenes whose uploaded
+ * videos have been probed. Scenes without uploaded videos are not included.
+ */
+export function useVideoDurations(
+  template: ExpressTemplate | null,
+  fieldData: Record<string, string>,
+): Record<string, number> {
+  const [durations, setDurations] = useState<Record<string, number>>({});
+
+  useEffect(() => {
+    if (!template) return;
+
+    // Find scenes that source video from form uploads
+    const formVideoScenes = template.scenes.filter(
+      s => s.segmentSource === 'form' && (s.type === 'intro' || s.type === 'outro' || s.type === 'content')
+    );
+
+    for (const scene of formVideoScenes) {
+      const fieldId = `segment-${scene.id}`;
+      const videoUrl = fieldData[fieldId];
+
+      if (!videoUrl || videoUrl.trim() === '') {
+        // No video uploaded — remove any stale duration
+        setDurations(prev => {
+          if (prev[scene.id]) {
+            const { [scene.id]: _, ...rest } = prev;
+            return rest;
+          }
+          return prev;
+        });
+        continue;
+      }
+
+      // Probe the video duration
+      const video = document.createElement('video');
+      video.preload = 'metadata';
+
+      video.onloadedmetadata = () => {
+        if (video.duration && isFinite(video.duration)) {
+          setDurations(prev => ({
+            ...prev,
+            [scene.id]: video.duration,
+          }));
+        }
+        video.remove();
+      };
+
+      video.onerror = () => {
+        video.remove();
+      };
+
+      video.src = videoUrl;
+    }
+  }, [template, fieldData]);
+
+  return durations;
+}
diff --git a/src/utils/expressCompiler.ts b/src/utils/expressCompiler.ts
index bdb3bc5..aa97e32 100644
--- a/src/utils/expressCompiler.ts
+++ b/src/utils/expressCompiler.ts
@@ -78,9 +78,23 @@ export function getAspectDimensions(aspect: string): { w: number; h: number } {
   }
 }
 
-/** Compute total duration of template in seconds */
-export function getTemplateDuration(template: ExpressTemplate): number {
-  return template.scenes.reduce((sum, s) => sum + s.durationSeconds, 0);
+/**
+ * Compute total duration of template in seconds.
+ * @param videoDurations Optional map of scene.id → actual video duration (seconds).
+ *                       When provided, overrides the static durationSeconds for scenes
+ *                       that source video from form uploads.
+ */
+export function getTemplateDuration(
+  template: ExpressTemplate,
+  videoDurations?: Record<string, number>,
+): number {
+  return template.scenes.reduce((sum, scene) => {
+    // If this scene has a form-sourced video and we know its actual duration, use it
+    if (videoDurations && scene.segmentSource === 'form' && videoDurations[scene.id]) {
+      return sum + videoDurations[scene.id];
+    }
+    return sum + scene.durationSeconds;
+  }, 0);
 }
 
 /**
@@ -92,6 +106,7 @@ export function compileExpressToTimeline(
   fieldData: Record<string, string>,
   designMD: DesignMD,
   company?: CompanyProfile,
+  videoDurations?: Record<string, number>,
 ): { elements: TimelineElement[]; layers: TimelineLayer[] } {
   const fps = 30;
   const elements: TimelineElement[] = [];
@@ -106,8 +121,11 @@ export function compileExpressToTimeline(
 
   // Process each scene sequentially — the template's scenes are the sole source of truth
   for (const scene of template.scenes) {
-
-    const sceneDurFrames = scene.durationSeconds * fps;
+    // Use actual video duration if available for form-sourced scenes
+    const sceneDuration = (videoDurations && scene.segmentSource === 'form' && videoDurations[scene.id])
+      ? videoDurations[scene.id]
+      : scene.durationSeconds;
+    const sceneDurFrames = sceneDuration * fps;
     const sceneStart = frameOffset;
     const sceneEnd = frameOffset + sceneDurFrames;