Automatically add .mp4 extension to video path

src/robofish/io/file.py

@@ -1471,6 +1471,8 @@ class File(h5py.File):
             )
 
         if video_path is not None:
+            if not video_path.suffix:
+                video_path = video_path.parent / f"{video_path.stem}.mp4"
             if video_path.exists():
                 if input(f"Video {str(video_path)} exists. Overwrite? (y/n)") == "y":
                     video_path.unlink()