A federal court in New York held that YouTube’s “notice and takedown” procedure – which, as the phrase indicates, allows copyright owners to notify YouTube of copyrighted content, which YouTube then takes down - protects YouTube from liability for infringing content posted to its site.  The Digital Millenium Copyright Act provides a “safe harbor” to companies that institute such procedures.  

The court held that YouTube’s general knowledge that others used its site to infringe copyrights does not make YouTube itself an infringer.  For more, see Professor Eric Goldman’s Technology and Marketing Law Blog.  Viacom has reportedly said that it will appeal.

Here is the court’s opinion.