DC Movie Maker won't output m1v....Now what?

[Neon]

Hi all.
I'm trying to get the Dreamcast movie maker to downsample some m1v files, but apparently my operating system won't allow it. (All other file types, yes, but not m1v.)
Anyone have any ideas as to what I can do now to downsample this movie type if DC M.M. won't do it? Or, anyone know what configuration I would have to change that's conflicting with DC M.M on my Windows '98 2nd Edition operating system? Any help would be appreciated