This is a real quick how to, I had my account moved to an FFMPEG PHP server to work on providing tips on FFMPEG.
In your php.ini file you will simply need to add the following line in the php.ini file to see FFMPEG on your phpinfo file.
Please note: this is only for servers that have PHP FFMPEG as some servers have python FFMPEG which will not show in PHP.
In the php.ini file add the following line: extension = ffmpeg.so
Now, you will see it included in your phpinfo file and then you can see what is used as well.