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.
Thanks for posting this Stagger...I can't believe it's been 22 years?! He's one of my guitar heros, along with SRV....what's with guitarists and flying? The day that I learned to play anything that Randy did, even poorly (and it was)