Verify mencoder works on your server.

Code:
/usr/local/bin/mencoder '/home/dubooth/public_html/video/Video1.wmv' -o /home/dubooth/public_html/flvideo/1224866847726420991.flv -of lavf -oac mp3lame -lameopts abr:br=56 -ovc lavc -lavcopts vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 -srate 22050 -lavfopts i_certify_that_my_video_stream_does_not_use_b_frames
This command should convert video into FLV, it it do not work, you have probem with mencoder installation.