See this post for some detail about output constraints:
http://blogs.adobe.com/toddkopriva/2010/06/output-module-constraints-in-a.h...
In this thread, Tim Kurkoski goes into a lot more detail about the constraints for AVI files:
http://forums.adobe.com/message/2973980
---------------------------------------------------------------------------------------------------------
Todd Kopriva, Adobe Systems Incorporated
product manager, professional video software
After Effects team blog
Premiere Pro team blog
---------------------------------------------------------------------------------------------------------
