Found this extension after Youtube switched to the new stupidly giant thumbnails - very happy to have that fixed, and some of the other tweaks look very useful too. Thanks a lot Pedro!

Another tweak that would be useful to add would be removing auto-translations (in general, but especially for video titles in the video grid)... But the separate extension I currently use for that (YouTube Anti translate) is sometimes a little bit buggy, and I suspect this might not be trivial to get right?