You can already do this with Sponsorblock.
> If a channel posts a review of a piece of hardware that was sent to them for free by the manufacturer is the entire video an ad?
Yes.
Considering YouTubers have to disclose paid promotions, this isn’t nearly as grey as your question suggests.
This is solved. Crowdsourcing. Look up sponsorblock
While the line is fuzzy, there's definitely a line. For example, when a video cuts away from the content to talk about a sponsor that's a clear ad.
> how would you expect any company to remove in-video "ads" without rampant accusations of censorship?
Removing would be somewhat difficult. Banning would not be complicated. Companies word those kinds of agreements all the time.
> If a channel posts a review of a piece of hardware that was sent to them for free by the manufacturer is the entire video an ad?
I'd say it depends, but the answer doesn't really matter. That's a straightforward category that can be allowed or not allowed directly, no need to worry about semantics.
Even so, I can see how someone could have those opinions if they strongly distrust attempts at restricting hate speech. The desire for a platform that lets you say whatever you want, but not in exchange for money, is something that makes sense.
I don't think it works that way.
If a channel posts a review of a piece of hardware that was sent to them for free by the manufacturer is the entire video an ad?