once they changed the laws to copyright upon creation, it was not as necessary to file copyrights
many people do not understand copyrights. pond5 said they needed a screenshot of my audio software to prove I owned my audio work. I told them I would send them my copyright registration for my music. they responded telling me that copyright registrations were not proof that I owned my music.
the copyright filing fee, last I checked, is $35 or so PER WORK. you'd have to file it per video for it to be valid, and you'd have to send each video on a separate dvd.
I told companies stock agencies that they should work with the copyright office to make everything easier for us, but they have not done so. istock did a meeting with the copyright office, that they announced after I asked them, but I don't know what came out of it.
copyrights are only proof that you register with the government. after that, if you ever have a legal problem, it is between you and the defendant and the courts (using your copyright registrations as evidence). there is no way to automatically prevent infringement.
your copyright is only good in your country, unless you pay a fee per country, and that only is eligible for some countries. forgot which convention regulated it, maybe the Hague convention?
its not worth it unless your work has a high existing value.