Look like your requirement instllation is not proper.

Try running following command in command prompt/terminal. If it do not convert video to FLV, you need to look into requirement installation.

Code:
/usr/bin/mencoder '/home/admin/domains/mysite.info/public_html/video/funny-video.avi' -o /home/admin/domains/mysite.info/public_html/flvideo/4ca4238a0b/1293706877382484294.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 -ofps 24 -vf harddup