I've heard people complain about the lack of granularity of uBlock Origin filtering compared to the no longer developed uMatrix add-on, and i've been one of those people. I still think Raymond's decision to abandon uM in favor of the allegedly easier to use uBO was a mistake and i'm certainty not alone. The pop-up interface of uMatrix always seemed more intuitive to me.
Some folks are adamant that uMatrix is superior to uBlock and is an absolute must-have, like breathing, however i'm not sure there's anything that one can do with uM that cannot be accomplished with uBO's filters, available in the 'My Filters' section of its settings. Other than adding a custom rule or two like
.../player/c4225c42/player_ias.vflset/...), URL rules aren't going to work for all of the stuff i wanted to block.
I ended up trimming a fair amount of lard from YouTube using static filters while still retaining the appearance and functionality i wanted. Here's the filters i'm currently using (if you're on mobile you may need to adjust):
||fonts.googleapis.com^$stylesheet,domain=www.youtube.com ||jnn-pa.googleapis.com^$xhr ||www.youtube.com/*/jsbin/custom-elements-es5-adapter.vflset/$script ||www.youtube.com/*/jsbin/intersection-observer.min.vflset/intersection-observer.min.js$script ||www.youtube.com/*/jsbin/scheduler.vflset/$script ||www.youtube.com/*/jsbin/serviceworker-notifications.vflset/$script ||www.youtube.com/*/jsbin/spf.vflset/spf.js$script ||www.youtube.com/*/jsbin/web-animations-next-lite.min.vflset/$script ||www.youtube.com/*/jsbin/www-tampering.vflset/www-tampering.js$script ||www.youtube.com/*/player_ias.vflset/en_US/annotations_module.js$script ||www.youtube.com/*/player_ias.vflset/en_US/embed.js$script ||www.youtube.com/*/player_ias.vflset/en_US/endscreen.js$script ||www.youtube.com/*/player_ias.vflset/en_US/miniplayer.js$script ||www.youtube.com/*/player_ias.vflset/en_US/offline.js$script ||www.youtube.com/*/player_ias.vflset/en_US/remote.js$script ||www.youtube.com/api/stats/*$xhr ||www.youtube.com/generate_204$xhr ||www.youtube.com/s/search/audio/*$media,domain=www.youtube.com ||www.youtube.com/sw.js$script ||www.youtube.com/youtubei/v1/att/get?key=*$xhr ||www.youtube.com/youtubei/v1/share/*$xhr