Installing ClipBucket but installation cannot find ffmpeg

I am running the installation of ClipBucket and I have installed ffmpeg. I rerun the installation to refresh the requirements and it continues to show:

Unable to find ffmpeg

If I do a find of ffmpeg, I find it though:

:~$ sudo find / -type f -name "ffmpeg"
/opt/ffmpeg/bin/ffmpeg

I am using Ubuntu 14.04.4 LTS with Plesk 12.5.30 Update #45, last updated at Sept 12, 2016 06:27 AM. Do I need to do something with Plesk for this to be seen by the web page?

Anyone have any suggestions?

Thanks!