[Mobile Replay - Bug] Video player plays wrong clip

[michellewzhang]

Replay example: https://sentry-sdks.sentry.io/replays/d4eade2316884da3b97ea53191ef58a5/?project=5428561&query=&referrer=%2Freplays%2F&statsPeriod=14d&yAxis=count%28%29

If you look at the first 4 seconds, the screen stops being black after 2 seconds, but pausing & playing at this spot is inconsistently black/not black. Also, after playing past 4 seconds, if you go back to 4 seconds, it'll show a black screen.

[michellewzhang]

Looked into this a bit. Seems to be a weird replay because in loadSegmentAtTime, segmentIndex is always undefined, which seems to relate to a gap: cc @billyvg

trim2.mov

sentry/static/app/components/replays/videoReplayer.tsx

Lines 555 to 560 in 1491155

	// and wait until the timer reaches the next video segment's starting
	// timestamp before playing.
	else if (segmentIndex === undefined && previousSegmentIndex !== undefined) {
	const previousSegment = this.getSegment(previousSegmentIndex)!;
	// XXX: Note that loading the previous segment will require waiting for