I’m customizing the FLVPlayback component with the individual video control components, but the SeekBar wouldn’t work no matter what I did, though the PlayPauseButton worked fine.
vidPlayer.seekBar = controls_mc.seek_mc;
Turns out that you need to set the SeekBar property of the FLVPlayback component AFTER you call play().
It took me a while to find the resolution to this annoying issue; hopefully google will index this post and help someone out.