It has only one issue: when playing the next video in a playlist for some reason causes the window to scroll down which leaves the top of the video hidden. This is not a minor issue and that's very unfortunate because this extension would be perfect otherwise.
EDIT 1: Reading back the review several users reported the same issue, some over a year ago.
EDIT 2: Workaround by commenting the scrollTo function in ythd.js and disabling auto-update.

iridium was better.

Auto scrolls down page a bit, cutting off top of video. Very annoying.

Everything else works great.

It keeps scrolling every youtube page and video just a bit so you cant see top of the page or video, supper annoying... I see other ppl have complain about it also, had to delete it for that reason, hope you fix it so i can install it again

Video 2x speed is not enough. Is it possible to add 2.5 , 3x speed?

Not auto pausing when I open a video or playlist item, in mobile or "request desktop' mode.

On android quality works but video speed does not.
Also, "Access data for all websites" is a privacy risk. I understand it is required to enable the extension for embedded videos but since this is not the most common use case for many, an option to disable this permission and only let it access youtube.com would be welcome.

Expanded mode does not fill the viewport, "Full page" overflows the viewport cutting off parts of the video, including playback controls and the scrobbing bar.

This addon causes random redirections to Youtube community posts every now and then. Can you please fix it? It's quite annoying.

Would have been nice, but random redirects to community posts instead of videos are annoying.

Excellent extension. Only reason for 3 stars is that it occasionally breaks Youtube. It just redirects all video links to random posts. Doesn't happen always but when it does, it just continues to happen for 20-30 mins which can get annoying.

I absolutely love this plug in but at the same time it can break Youtube. Issues with playing a video and it randomly sending you into a loop on some random profile. I really wish they'd fix this problem.