Update app.py

app.py

@@ -40,7 +40,7 @@ def process_video(video):
 
     temp_dir = tempfile.mkdtemp()
     output_path = os.path.join(temp_dir, "annotated_video.mp4")
-    video_writer = cv2.VideoWriter(temp_dir,
+    video_writer = cv2.VideoWriter(output_path,
                             cv2.VideoWriter_fourcc(*'mp4v'),
                             fps,
                             (frame_w, frame_h))