When you have millions of passionate people sharing moments from movies to music videos that they love that is a hard thing to stop. Copyright holders should be rejoicing that people love their content and learn that it will be nearly impossible to control where their media is distributed. While I believe people should be able share moments of material in accordance with fair use standards, I can sympathize with media creators frustrations when whole bodies of work are stolen.
Media creators do have to get a grip that times have changed embrace what is occurring, instead of sending DMCA takedown notices. It makes a lot more sense to work with YouTube and others media sites to monetize that shared content.
While I know Viacom will fight this all the way to top of the court system, my hope is that YouTube will prevail when the decision is appealed and we can claim a final victory on the safe harbor provisions.