> Maintaining a list of the top 1,000,000 bands in the world and not letting anybody upload tracks with metadata that included those bands and song names in it would not be that difficult.

I addressed this in my other comment, but as it turns out, this aspect of the problem is incredibly difficult. Metadata can be wrong and we can't always depend on it. So we use waveform analysis. But thats difficult too due to the indexing and storage requirements and the accuracy of the algorithm performing the search. Also this list is not finite. It changes constantly and parties are always bickering over rights to content and that takes time to sort out. We actually have a team of people who handle takedown requests, and we have another team of people who put in the necessary restrictions to keep content from getting played or uploaded.