Suggestion: people know an ad when they see one. Even if someone is subscribed to a YT channel, they're not gonna sit through a video, "Here watch me unbox this

Suggestion: people know an ad when they see one. Even if someone is subscribed to a YT channel, they're not gonna sit through a video, "Here watch me unbox this thing that a not-sponsor sent me!", because it feels like the "content" is an ad. You'd probably be better off asking them to give it screen-time in the same way that podcast advertising currently works, where the host devotes 20 or 30 seconds at the beginning or the end of the show to talk about Sponsor X.