The problem is with mencoder.

Code:
/usr/local/bin/mencoder '/home/internev/public_html/video/Video10.avi' -o /home/internev/public_html/flvideo/11915891961375430862.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
If your mencoder installation is proper, above command will convert the video to FLV format and will be available at

/home/internev/public_html/flvideo/11915891961375430862.flv

If this file is not created, the problem will be with mencoder installation.

You can ask your web host why the command is not converting AVI video. Since this is a common format, it may be mplayer installation problem.