you dont need a copyright as you own em in the first place.
We were just talking about this on TVN
Some pretty good info here.
http://www.tornadovideos.net/forum?func=view&catid=11&id=18769
and heres the place to go to get the complete info on the law and so on
http://www.copyright.gov/
They always say that when photographers have plumbing questions, they call a plumber. When they have legal questions, they ask... other photographers.
I am no attorney, however, from my own personal experience, I can say the following:
1. Putting copyright watermarks on your images vastly decreases the likelihood they will be infringed. This could be because people don't want to take the time to remove the watermark, though my hunch is that it's because some people (erroneously) think that everything on the internet is free for the taking unless it has a copyright notice on it. If they see the notice, they go "Oh, that's not free. I'd better find something else."
2. Putting copyright watermarks on your images vastly increases your leverage should some knucklehead infringe your photos, both due to the "willful infringement" enhanced damages clause in Title 15, Chapter 5, § 504, and the DMCA.
You don't need to do anything fancy, just put "Copyright 2009 Your Name" or "© 2009 Your Name". The year, of course, changes depending on when you took the image or video. It also helps to add metadata inside the image or video itself that specifies that the image is copyrighted and that it can not be used without license.
Lastly, you MUST MUST MUST register your copyrights with the U.S. Copyright office and you must do this BEFORE your images are infringed, not after.
Do these things and you will be in a very strong position if you suddenly find a company infringing your images or video.
You can find a wealth of information on this topic at
http://photoattorney.com.