If you're thinking of a watermark to protect your work against theft, they're often easy to remove or obscure, and a watermark for brand recognition, like was said, could be a distraction to the viewer. What might be cool though, would be to integrate your name into your videos. Take your "Murder, Not An Accident" video... on the cop car, rather than it saying "Police" it could say "Amuse Your Brain" and the "P" over the star changed to "AYB". It's subtle, but crosses right in the viewers line of sight... a powerful place. It's moving, which makes it hard to remove... more protection. And if each of your videos were to have a cop car or ambulance or fire truck, etc. crossing the screen, viewers might become intrigued by the novelty and look forward to it as part of the fun of watching your videos... like the Easter eggs in Pixar movies. And, they'll know if they see a video like yours, but don't see your name on the side of a vehicle, that it's not an Amuse Your Brain video.
