I had a contributor for the Renderosity Video loop who sent his stuff in using MPEG4 from QT6. I installed QT6 on a machine that had OS 8.6, converted it to "animation" compression, and then transferred it to my primary machine (I didn't have QT6 on that). No problems there.

Before they made me they broke the mold!
http://home.roadrunner.com/~kflach/