Does anyone know why the tag information is not stored in the AVI file, like with my MP3s?
So far as I understand it (and I'm far from an expert on video related stuff) video file standards don't support metadata in the files. Search around here a bit and you'll find more in depth info about this subject.
There are definitely other tools out there, but if the only drawback to the one you've got is needing to keep the filename the same, I'd say the one you have is the one to go with. Unless of course it is for some lame reason tedious to keep the filename the same. That's a different story...
-JB