Dunno if this will help or not but I did a forum search for your error and got these forum thread results

http://www.google.com/custom?domains=fo ... %3A1&hl=en

I searched for

Return value: Exiting... (error parsing command line)

Running flvtool2: /usr/bin/flvtool2
sounds like mencoder on your server got borked and needs to be reinstalled? Or they changed mencoder on you and you need to change the convert commands in your video_conversion.php? viewtopic.php?f=4&t=1707&p=7581