I have downloaded a movie, converted it to AVI

File support varies depending on the model Mambo you have purchased. The conversion utility included with your Mambo player can convert most AVI files into a compatible format for your player. Consult the comprehensive user's manual on the CD included with your player for specifications. Specifications are subject to change without notice.
I don't know if you used their software (MusicMatch Jukebox) but thatis what it suggests..

I don't know what you have not tried. So I am sorry that my options for you are limited.

Thank you dor the chance to help

Randy