converting FLV to MPG

sudo apt-get install ffmpeg 

ffmpeg -i video.flv -ab 56 -ar 22050 -b 500  -s 320x240 video.mpg 

finally to make your life easier just put it a script file to excute later

mkdir ~/scripts;
echo 'ffmpeg -i $1 -ab 56 -ar 22050 -b 500  -s 320x240 $1.mpg' > f2mpg.sh;
mv Flv2Mpg.sh ~/scripts 

now whenever you want to convert FLV file to mpg just shot the

 ~/scripts/f2mpg.sh Flv_video_file_name.flv