Just a FYI about the Perian plug-in / Quicktime playback:
I was viewing a .flv file in Quicktime after installing the Perian plug-in. The video consists of a white background with a woman walking into frame and animated objects gliding behind her. In the Quicktime play back I noticed gray pixel noise trailing my animated elements. I assumed it was just part of the compression process. However, once I created my .swf to play the .flv back for Flash and played it in the Adobe Media Player the gray noise is no longer there.
So while this plug-in is a great tool for quick .flv review in Quicktime, I wouldn't recommend it as the final viewing option for a Flash video. Also, this does not work with new .f4v files.