fixed bugs

sentence_api/main.py

@@ -481,9 +481,13 @@ def create_app(
         media_path = service_settings.videos_dir / row["stored_filename"]
         if not media_path.is_file():
             raise HTTPException(status_code=404, detail="Stored video file is missing.")
+        media_type = row.get("content_type") or "video/mp4"
+        if not str(media_type).lower().startswith("video/"):
+            guessed = mimetypes.guess_type(str(row.get("stored_filename") or ""))[0]
+            media_type = guessed if guessed and guessed.lower().startswith("video/") else "video/mp4"
         return FileResponse(
             media_path,
-            media_type=row["content_type"],
+            media_type=media_type,
             headers={"Accept-Ranges": "bytes", "Cache-Control": "public, max-age=3600"},
         )