Piracy protection and online marketing of ipod videos?

[PDX_DVX]

I am just throwing an idea out there to see what the possibilities are. Say that you produced a video that had different segments to it, and you wanted to make those available for download onto video ipods for a small price, say 2 bucks per. What would be the best route to go about doing this, and is there any way to put some sort of piracy protection on it, to prevent one person who buys it from sharing? As in some sort of digital watermark? I tried a search on this but couldnt come up with much...