Yikes. Is anyone else having this same problem out there? You’re exporting a Quicktime .MOV from Flash CS3 on a Mac. You play it back and BKRSHHKRK! A character on screen moves and leaves behind a trail of pixelly crud (see the above picture). I’ve been wrestling with this for months now, searching for an answer on bulletin boards and such. I believe the term is “artifacting”. Pixels from previous frames staying on screen when they shouldn’t.
The only solution I’ve so far found is to laboriously save down to Flash 8 and export it from there. It always works with no problem. But if anyone out there has found a way to successfully export perfect Quicktimes from Flash CS3, PLEASE leave a comment with your sage-like wisdom.