Clip Theft: What to do?

[foxestacado.livejournal.com]

I do not know what to do. I found a video that is 90% made up of clips lifted from my videos. This person even lifts entire sections (two or more clips together) to put in her video. I have written two very civilized, gently-worded emails to this person. I tell her/him over and over again that I understand if she is a newbie and does not understand that clip theft/plagarism is not allowable by me. But this person have not yet responded. What should I do now?

ETA: Everything is sorted out between me and this person. She did not understand that it was wrong to take footage from other videos. However, I am still interested what you guys have done in the past with regards to clip theft.