Have you registered a 'DCMA takedown agent' with the Copyright Office?
This is an obscure bureaucratic prerequisite to enjoying a legal “safe harbor” from copyright lawsuits over third-party posts and the registration fee is only $105.
See this Wired article for more info:
http://www.wired.com/threatlevel/2010/10/dmca-righthaven-loophole/
Here are a few other strategies, etc.
http://www.godlikeproductions.com/forum1/message1146844/pg1

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