The host is deceptive. Find out the version, newer versions of mencoder and ffmpeg needed another change in the encoding line.

But that error is because they do not have ffmpeg installed properly. Give them the command line to run and ask them to check that. My experience shows that they fix the problem, report that it works fine and then everything is ok.

Right now I am having a problem with the encoding. It is not working and I wonder if it is not the upgrade they did to php. I am not getting that not found, something else.