for track in tracks:
if not isinstance(track, dict):
continue
- if track.get('kind') != 'captions':
+ track_kind = track.get('kind')
+ if not track_kind or not isinstance(track_kind, compat_str):
+ continue
+ if track_kind.lower() not in ('captions', 'subtitles'):
continue
track_url = urljoin(base_url, track.get('file'))
if not track_url: