How can an "unkown format" have a known format???

[Dunnyman]

I've been trying for ages to convert a file, but no matter WHAT preset I use, it starts, and 1 second later it says finished, then the log or terminal output says "uknown format", with NO other output available, that is ALL I get! However, the file plays perfectly fine in VLC, and VLC reports DivX video, 576x432 and vorb audio, 41000Hz, 48807 bitrate, so how come these well known audio and video codecs are showing up as "unknown"?
Is there ANY tools for checking avi headers and fixing them? Does anyone know where the avi creators live, so I can have them whacked? It has to be the crappiest way to encode ANYTHING!!!! I have tried damn near every preset in ffmpegX, and all fail, so any help would be much appreciated, otherwise I'm just gonna chuck this file and give up, the $%^&*^$#@ thing isn't available on DVD, and this is a VHS rip from a friend of a friend, who, apparently, has the IQ of a turnip!! Or does anyone know of a VHS to DVD service that can do it for me?

[Case]

Try demuxing the AVI, then transcode video and audio separately.