Aren't those just iframes, which is effectively just youtube loading inside an existing web page instead of its own tab. I would assume first party cookies would work just fine for this.
Nope, an iframe on an unrelated site is exactly what turns it into a third party cookie. (The user and the site they're visiting are the first two parties; the embedded site is the third party.)
Put another way, an ad iframe loading a tracking (identity) cookie is indistinguishable from a YouTube iframe loading a login (identity) cookie.
i still don't follow. i guess my point is, when an embedded video loads for me, youtube still knows that it's me. it gives me the same recommended videos i'd get if i were on youtube.com directly. so i assume since i pay for premium, it'd also skip ads on embedded videos too. i wouldnt know because i use ublock.
> when an embedded video loads for me, youtube still knows that it's me
If/when third party cookie blocking is fully deployed, this won't be true. Your browser won't send YouTube's session cookie to YouTube when it's loaded in an iframe on an unrelated site, so YouTube won't know you're a premium user.