It seems there is problem with your mencoder installation on server. To verify, run the command

/usr/bin/mencoder /home/scorio/public_html/video/8.avi -o /home/scorio/public_html/flvideo/8.flv -of lavf -oac mp3lame -lameopts abr:br=56 -ovc lavc -lavcopts vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:l ast_pred=3 -srate 22050 -lavfopts i_certify_that_my_video_stream_does_not_use_b_fram es
On SSH prompt and see if it can convert video into FLV format (home/scorio/public_html/flvideo/8.flv)

If you have no SSH access, you can ask your web host to do it for you or run the command from PHP script, for more details, read

http://forums.buyscripts.in/viewtopic.php?t=351