WARNING: ffmpeg does​ not exist - not con​verting flv file​

[computing at windcheetah.org.uk]

Hi, has anyone else started getting the warning message above???

It started a few days ago, but when I enter the command 'which ffmpeg' it finds
it at /usr/bin/ffmpeg

Does anyone know what might be going on????

I am running v2.82 on Linux Mint with the 3.2.0-37-generic kernel.

Thanks loads

Martin