=) I mostly use watermarks now to cover my ass from studios (like a sort of "Look! This is *Disney's*! I'm not taking credit from them!" kinda deal). And you're right, the only way to really prevent stealing source is to watermark the very center, or as close to the center as you can stand, and even then it's possible to get around it by blurring or using masks or photoshopping (if you're willing to do it frame by frame). I'd mostly wanted to get this info out so that if people wanted, they knew how.