We I guess you can install their software as they state and find out what is needed to play a file meaning what there embed code is and you would need to create a new embed template say call it embed-flv.tmpl and put whatever html you need to do call that player to play our file. You can use by example the other embed templates to see how we do it. I cant tell you what would go in there as I have never seen this software or used it. You would upload your new template to the proper template directory. To add support for your new video embed template you would add this to showphoto.php around line 756 add this in bold.
Content visible to verified customers only.