"You should o point out to people that if someone sends a copyright takedown to YouTube over your video, you can always "counternotice" to YouTube that it is a fair use and it will go back up within 10-14 business days unless the copyright owner sues you.
http://www.youtube.com/t/dmca_policy
http://www.google.com/support/youtube/bin/answer.py?answer=59826&query=counter&topic=&type=&hl=en_US
While being sued is certainly a risk people shouldn't take lightly, in weak cases, the chances are pretty slim that they will actually take you to court."
--Jason Schultz of Law Geek
(this advice came out of a Fair Use incident that John of Total Vom found himself in. He successfully stood up for his Fair Use rights and solved the problem diplomatically)
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This is assuming you already contacted that Youtube user and asked to kindly remove your video.
1. Head out to http://www.youtube.com/copyright_complaint_form and file the complaint.
2. If the original video file of yours is in possesion of that Youtube user you're dealing with, threaten to file a small claims lawsuit, provided you made the video yourself, completely shot and edited, sountrack, graphics etc.
3. If your warning doesn't work, sue the sucker to consent to delete your video from his/her hard drive(s) on all computers in his/her possesion. With a consent that this video will never appear on the internet again. Falure to comply, you seek monetary reimbursment that is a sum of all expenses associated with you producing that video. Add your travel and filing the complaint expenses. In Brooklyn NY the cost is $20 for a complaint up to $5,000