YouTube is not usable in Orion 0.99.130.1-beta (WebKit 619.1.11.111.2) under MacOS 12.7.6 ("Monterey") on an Intel MacBook Pro. There is only one extension installed, and it's not relevant to this situation (1Password).
In the attached movie we see a typical attempt to watch a YouTube video: first we see a still from an ad, then we get blocked with YouTube's bogus "Ad blockers violate the terms of use" (no, they don't; there's nothing in YouTube's terms that mentions ad blockers, but that's beside the point).
I change the user agent to Chrome, the page reloads, then after awhile an ad loads. It eventually fast-forwards, then there are multiple seconds of black, then another ad loads, it eventually fast-forwards like the first one, then another multiple seconds of black (etc) then the video eventually loads—but only the first short bit of it. We only get to see 17 seconds of the video before it hits the end of the part that loaded, and no further loading will happen. It will sit there with the loading-circle animating forever, if I let it.
This second movie is Firefox 133.0.3 running on the same machine, with many extensions installed. Potentially-relevant ones include AdGuard Browser Assistant, Disconnect, Ghostery, Privacy Badger, and uBlock Origin. I'm not sure which one(s) are doing the heavy lifting, but whatever their division of labour, I see not even a trace of a YouTube ad, nor any black-screen placeholder. Here's that same YouTube video in Firefox: load, play, and it just…does it, progressively preloading more of the vid as it plays along:
0.99.130.1-beta (WebKit 619.1.11.111.2)
Monterey (12)