Update app.py

app.py

@@ -17,6 +17,6 @@ with col1:
     st.video(video_bytes)
 
 with col2:
-    video_file1 = open('Demo', 'rb')
+    video_file1 = open('Demo.mp4', 'rb')
     video_bytes1 = video_file1.read()
     st.video(video_bytes1)