Parent: $root.$constants
| kJSVideoTrackKindCaptions | Constant for track kind = 'captions' |
| kJSVideoTrackKindChapters | Constant for track kind = 'chapters' |
| kJSVideoTrackKindDescriptions | Constant for track kind = 'descriptions' |
| kJSVideoTrackKindMetaData | Constant for track kind = 'metadata' |
| kJSVideoTrackKindSubtitles | Constant for track kind = 'subtitles' |