I can't find the vid online, but Will Ferrell played the cowbell with Queens of the Stone Age when he hosted a couple seasons ago. So maybe you were thinking of both performances and got them mixed up? Either way, the QOTSA performance was hilarious. I'd look for that too.
THE TOP SELLERS 1. Order of the Black (The W at Amazon) Black Label Society (E1 Music) 2. All About Tonight Blake Shelton (Warner Bros.) 3. Camp Rock 2: The Final Jam [Soundtrack] Various Artists (Walt Disney Records) 4.