Hello,
I just wanted to make one correction. "DivX 5.2.1 for Mac is compatible with Mac OS 10.2.6 through OS 10.3.9." - http://www.divx.com/divx/mac/pre10.3.9.php
For 9.1, try using 5.1.1, at http://www.macorchard.com/helper/
Also, you need to remove any 3ivX files from the extension...
"The latest version for OS 9 is Divx 5.2.1."
Correction, "DivX 5.2.1 for Mac is compatible with Mac OS 10.2.6 through OS 10.3.9"
For OS 9.1, you can use 5.1.1 http://www.macorchard.com/helper/