There's an EFF fair use test case involving a YouTube takedown of a toddler bouncing around to a 29 second clip of a Prince song playing in the background: Lenz v. Universal. It was filed in 2007 and has yet to be resolved.

The fact is that while section 512(f) of the DMCA provides consequences to misrepresentations by those making takedown requests, it is damned impossible to actually enforce that.