Affiliate Marketing Secrets

I understand their material is copyrighted. Is there something I can do to make it clear that I don’t own the content, nor claim to? I was thinking of something like switching off monetization (which I wouldn’t have put on anyway), or writing a comment in the description saying something like “this content is wholly owned by the BBC. I own no part of it.”
Thing is, I’m trying to post a clip from Top Gear. I know that they have their own YouTube channel, but I still see hundreds of other TG videos from people who aren’t affiliated with Top Gear or the BBC in general. Why are they allowed to post TG stuff?