As noted in bug 1131482, the first two bitdash demo videos ("Sintel") have subtitles in Chrome, but not Firefox. karlt says text tracks are part of the MSE spec. * Sintel (Multilanguage & Subtitles) - SegmentTemplate: http://www.dash-player.com/demo/streaming-server-and-encoder-support/?mpd=http%3A%2F%2Fbitcdn-global.bitmovin.com%2Fcontent%2Fsintel%2Fsintel.mpd * Sintel (Multilanguage & Subtitles) - SegmentList: http://www.dash-player.com/demo/streaming-server-and-encoder-support/?mpd=http%3A%2F%2Fbitcdn-global.bitmovin.com%2Fcontent%2Fsintel%2Fsintel-seglist.mpd

I don't think this needs to block the EME MVP.

The issue is not actually related to MSE. The captions are not shown because: 1. It's disabled on purpose for Firefox, see https://github.com/Dash-Industry-Forum/dash.js/blob/development/samples/dash-if-reference-player/app/main.js#L571 2. We don't support TextTrackCue.onenter/.onexit events (bug 996333) 3. We don't support ::cue styling (bug 865395) 4. The application uses non-standard CSSStyleSheet.addRule (implemented in IE and WebKit)

Almost forgot: 5. The textTracks property of a video might not have track listed (bug 1206304)

Changing the dependency to different meta bug. The CSSStyleSheet.addRule (from comment 2) was addressed via https://github.com/Dash-Industry-Forum/dash.js/pull/803. The main blocking bug now is bug 996333 -- implementing cue onenter/onexit events (rest of them can be fixed by workarounds).