It's really great, but there are two things that could be improved a bit. Firstly, when you hide the thumbnails, it also hides the progress bar that shows how much of the video you've watched. I would really like an option to keep that bar visible. Secondly, it slows YouTube down noticeably. I'm pretty fine with that and just wanted to mention it. Thanks for this add-on! (Note: I'm using this on mobile, so I'm not sure if this happens on PC.)