If you wanted to, Jen, you could set up a new yahoogroup just to upload the trailer into. If there's nothing in the "files" section, you can zip the trailer file and it should be just small enough to fit within the 20MB limit.
That's about the only possibility I can think of. Once I get the darned thing downloaded on my home computer, I can host it at my site and/or set it up in another yahoo group for us. Sorry I haven't been able to do it yet, but I still don't have the file. Grrrrr....