Fix video streaming

[vgarleanu]

Currently video.js is very picky about streams. Streaming with nightfall works fine in MPV and Vlc, however its partially broken in browsers and more specifically video.js.

This is because video.js is very strict about segment continuity. Because of this seeking doesnt work, and hard timeouts (ffmpeg getting killed after a timeout instead of being issues a SIGSTP) have to be disabled. On further inspection video.js crashes because when ffmpeg is restarted with a new timestamp offset, the fragments it outputs also have a timestamp offset that is reset to 0, and because init.mp4 is never reloaded by videojs automatically video.js thinks that the segment requested is actually older than it is, thus it tries to fetch the next segment infinitely until it gets a valid segment timestamp offset.

We can fix this two ways, either we patch video.js to be more lenient, or when we seek in a non-transcoded region we restart video.js and reload the dash manifest (this needs to be paired with soft-timeouts for transcoding sessions).

[vgarleanu]

Perhaps we could open a issue on the video.js repo and ask the developers if there is a better way to handle this.