Fails to auto-pause foreground tab video auto-play and very often also fails to enforce this on background tabs too.
Also it's ad-removal feature can put the video in an awkward loop, effectively failing to remove the ad and restarting play from the beginning of the video.
Wish these could be fixed, because they are the only features that are actually of use to me in this extension (I don't really use any of the other features, i.e. can do without them)