Detect video docs by file extension

backend/main.py

@@ -226,8 +226,22 @@ def fmt_dur(seconds: int | None) -> str:
 def extract_vid(msg):
     if msg.video:
         return msg.video
-    if msg.document and msg.document.mime_type and msg.document.mime_type.startswith("video"):
-        return msg.document
+    if msg.document:
+        mime = getattr(msg.document, "mime_type", None) or ""
+        if mime.startswith("video"):
+            return msg.document
+        file_name = (getattr(msg.document, "file_name", "") or "").lower()
+        if file_name.endswith((
+            ".mp4",
+            ".mkv",
+            ".mov",
+            ".avi",
+            ".webm",
+            ".m4v",
+            ".ts",
+            ".m2ts",
+        )):
+            return msg.document
     return None