prevent cache

app.py

@@ -221,7 +221,12 @@ def preview_video(file_id):
         if not os.path.exists(output_path):
             return jsonify({'error': 'File not found'}), 404
         
-        return send_file(output_path, mimetype='video/mp4')
+        response = send_file(output_path, mimetype='video/mp4')
+        # Prevent caching
+        response.headers['Cache-Control'] = 'no-store, no-cache, must-revalidate, max-age=0'
+        response.headers['Pragma'] = 'no-cache'
+        response.headers['Expires'] = '0'
+        return response
     except Exception as e:
         return jsonify({'error': str(e)}), 500
 

templates/index.html

@@ -1253,9 +1253,9 @@
                     throw new Error(data.error || 'Processing failed');
                 }
 
-                // Load processed video preview
+                // Load processed video preview with cache-busting
                 const processedVideoPreview = document.getElementById('processed-video-preview');
-                processedVideoPreview.src = `/preview/${currentFileId}`;
+                processedVideoPreview.src = `/preview/${currentFileId}?t=${Date.now()}`;
                 
                 // Show download section
                 document.getElementById('edit-section').classList.add('hidden');