Removing stamps from videos

[Unclebananahead]

I have a number of "Discovery Channel: Education" videos I downloaded from a teaching resource website for some school, but virtually all of them have a Discovery Channel stamp on one of the lower corners. I need a way to remove it, or cover it with my own logo, so I can utilize material from the foregoing in my video projects.

[Unclebananahead]

They're .asf files. So, does anyone know? I'm thinking it may require some sort of video editing software. I'd prefer something open source if possible.


Maybe something like Cinelerra? I want something easy to use.