I get it's expensive, but if you don't want to share it for free on a forum that is designed for this purpose then just don't share it. Plus I'm sure a watermark is not the best way to make a video untraceable.
Dude, what's with all the threats like it's you who's made the video. I appreciate you've bought it for yourself but if you going to act like you own the whole rights to it then don't give it out.