This is that bloody elusive mp42 and mp43 decompressor used for .avi files. Just unzip this file, read the Readme file and follow the instructions given there. Simple, and it works. Trust me. -)))
The following files are found inside the driver download file.
|mpeg4fix.inf||1.3 KB||5 Oct 1999|
|MPG4C32.DLL||416.3 KB||9 Apr 1999|
|READ THIS FIRST!.txt||2.3 KB||5 Apr 2000|