I've always wanted a program like what you describe, but I have found that currently there is no way to tag an avi file in the way you describe. What I did was use Handbrake to transcode the files to mp4 (a better format anyway) and then tag then with MetaX.
Afaik AVI does not support any metadata tags, it's an obsolete container format from way back. Ideally you'd switch containers (without transcoding the audio or video), which is quick and painless. Then you could use a tagger.
The AVI container supports quite a lot of metadata tags, but the only programs I've seen that can write them are for Windows, abcAVI and Movie Library ++ being a couple of them.