The actual function works, but only under tight parameters, and not perfectly well.

The video seems to lose frames occasionally, not appearing totally smooth. But the big issues are that you can't navigate with arrow keys anymore, as the video skips back, but the audio keeps going.

Sometimes it needs to be refreshed to get the correct millisecond-correction going again.

It takes a few seconds to get the audio going hitting play from a pause. The worst is not being able to jump back or forwards, though hitting the space bar twice (pause then play) fixes it.

I just went to another tab for a while and when I got back, the video and audio were out of sync. Before I left, they were fine.

I would definitely prefer to be able to skip by 5ms and 10ms and 20ms instead of just 1ms adjustments, too.

I really want this thing to work, because I have a lot of use for this extension! I also have Enhancer for YouTube going, as well as uBlock Origin and an Audio Equalizer extension too, so maybe those are affecting things, but that would be lame if they were.