Add validation to process_new_user_message to restrict multiple video uploads

app.py

@@ -45,6 +45,9 @@ def process_new_user_message(message: dict) -> list[dict]:
     if not message["files"]:
         return [{"type": "text", "text": message["text"]}]
 
+    if len([path for path in message["files"] if path.endswith(".mp4")]) > 1:
+        raise gr.Error("Only one video is supported at a time.")
+
     if "<image>" in message["text"]:
         content = []
         logger.debug(f"{message['files']=}")