Interesting post at AdLaw by Request: Ad agencies presumably like it when other people repost their commercials without authorization, but they don't want to pay the performers any additional fees. The performers, who don't have any copyright interests, seek such fees for YouTube appearances and/or want the agencies to send DMCA takedowns. The agencies take the position they have no obligation to send takedowns, which are most likely not in their/their clients' economic interests.
If any performer sues YouTube, what result? It's Brown v. Ames, or maybe Fleet v. CBS, in the age of the DMCA. Is there such a thing as DMCA preemption? Does the DMCA add anything to the copyright preemption analysis? Does the copyright owner's careful hands-off policy support or undermine the idea of a conflict with copyright rights?
Somebody should write a note!