How to enforce copyright?

So, there is a kid on youTube that used one of our logos as a backgroundimage for his profile site. No big deal, however we would like to have been asked. BUT what the kid did shows he is a tad bit unexperienced about good manners. Not did he only use our logo without asking, but he linked it from our server and generated quite a bit of useless traffic, without even providing a link to us. So what I did is change the image to another one promoting the sequel to the game whose logo he 'borrowed'. Lesson learned Zack?