The problem is mencoder is not able to convert the video to FLV format.

Code:
/usr/bin/mencoder /home/xxxxxxx/video/popeyenaturalthingtodo.mp4 -o /home/xxxxxx/flvideo/1192470423497519261.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
Ask your server admin or web host to run this command and see if video is getting converted to FLV.

If mencoder is not able to convert video to FLV, it is problem with mencoder installation.