Ben is right, as usual.
Anyone who really, really wants to copy something will find a way to do so. And even once the video is out of the original DVD, the only way to ownerproof video these days is to run a bug from start to finish, which is what almost every network is doing, including PBS.
Unfortunately, some bugs are so irritatingly intrusive, like the one used by my local KCET (Los Angeles); it often covers critical graphic elements of what I'm watching!
No wonder in the UK bugs are called DOG (digital on-screen graphic).
Sorry, Joe. Even watermarking might not stop piracy.
Alberto