The RIAA has gone straight into self parody now. Mike Arrington notes that they are torqued at users of online video sites like YouTube:

The RIAA is apparently sending out cease-and-desist letters to YouTube users who dare to put up videos of things such as themselves dancing to music they haven't licensed. It's difficult to see how the RIAA can make a credible claim of "losses" in this case. Clearly, some kids videotaping themselves bopping along to some song aren't going to pay a license fee -- and these sorts of viral videos tend to help build up more interest in artists. So what good does it do to go after these videos?

They've apparently decided that they have to address every single thing that could possibly be defined as an infringement, on the grounds that not doing so would lead to a slippery slope. As Mike says, they haven't stopped to ask what possible revenue losses are coming from this kind of thing.