When you shoot a video, a copyright is automatically applied to it. You own your video even if you don't register it. A video doesn't have to have music to be copyrighted content. It's against the law, and against youtube policy to just copy someone else's video. The reason I don't want copies of my video is because people make claims that aren't true in my name. When someone else uploads my video and 50,000 people view it, they think that when that uploader makes comments, that it's ME responding. I don't want other people pretending to be me. They also tend to assert things about me that are untrue. The most common is that I'm a law student. I've never been a law student, and claiming I'm a law student implies that only a law student could have an understanding of the law. It's really not that hard for the everyday man to learn the law and follow it.