That you gotta now disable all other adblocking setups on YT for uBlock Origin to have the best chance of working. Even PrivacyBadger will interfere now. This includes turning off Firefox's Enhanced Tracking Protection on Youtube (the little shield icon in the address bar - click it for options. It's per-site, so just for YT, don't worry.)
UPDATED: @plumpan has linked a great chost about other, specifically off-site not-on-Youtube ways of getting around this mess if uBlock Origin meets its end on the battlefield - it's called FreeTube, it's in the linked chost above, go check it out!
I've just been running uBlock Origin (and YTEnhancer+SponsorBlock, but those are different), keeping it up-to-date, and it's been flawless so far.
If you want it to work properly and you've not got it autoupdating, you really need to follow these steps properly and fully. Yes, that does mean disabling ALL your addons, removing ANY custom filters for Youtube, and basically starting from scratch with a clean, recent copy of uBlock Origin.
Right now, Youtube is directly trying to counter uBlock Origin in some manner. @mocha has a great little backup userscript to automatically embed the video you want to watch into an iframe, which is the other, manual way to watch the video. Excellent to have as a backup.
At this point? Don't be afraid to pirate your favourite videos. Seriously. Download them if you want. Use something like YT-DLP to rip vids where possible.
It might be important, soon. Just saying.
It is, in the end, zero percent possible to transmit data to someone else's computer without them being able to Have The Data. Companies hawking copy protection and DRM schemes have been trying for decades but until they physically lock our computers away from us completely it's not actually possible
