Sorry for late reply.
Here's the file and line where the path is specified:
The are several lines you would need to edit:
line 229: add /path/to/ffmpeg/installation/ before running ffmpeg command as such:
/usr/bin/ffmpeg -y -i ".$source." ". $extra ." ".$target;
line 282: add /path/to/ffmpeg/installation/ before running ffmpeg command as such:
/usr/bin/ffmpeg -y -i ".$source." $extra ".$target;
We originally had a path as such /usr/local/bin/ or /usr/bin/ but turns out that some users have different installation paths than the general one.
If the server configured properly, you should be able to run ffmpeg command from the terminal without specifying the path to the installation.
However, in some cases you might need to specify it.
If you have ssh access (I assume you do, since you installed ffmpeg), try running encoding command from the terminal as such:
ffmpeg -i /path/to/video.ext /path/to/image%d.jpg
See if the image is being generated from the video.ext or if not what error responses are you getting. It might be helpful in debugging the issue.
If you continue having issues, please feel free to email me at firstname.lastname@example.org.