AaronAMV wrote:Probably DivX or XviD.
Dont make me post the madly flashing banner that says
"DON'T EDIT WITH DIVX/XVID FILES IN WMM"
I suggest you use virtual dubmod to create some lossless avi files to edit with instead. Sure they will be big but they will stop your program from eating your project file in some random "why is this person using these kinda files in me?" way.
There are several threads in the forum (like over 50% of them) that tell you what codecs you should be using and how to make files in those codecs.
Read ErMaC & AbsoluteDestiny's Friendly AMV Guides
will also help you as it talks about preping footage for WMM.