Will these paths work okay?:
/usr/bin/mplayer
/usr/bin/mencoder
/usr/bin/flvtool2

If you already know your host has the correct mplayer ffmpeg and stuff installed try this in config.

/usr/local/bin/ffmpeg
/usr/local/bin/mplayer
/usr/local/bin/mencoder

FLVTOOL2 Will be right with what you have now.[/quote]