Hi Hamish and welcome to the forum!
That's a very impressive site - I've no idea how it's done! All I can say is that he's probably using an SBS box, as he's picking up a Nextjet Beech 1900 which a bug in RadarBox means that we can't locate. AirNav should be fixing this bug in the next software release, due in the next few weeks.
Enjoy!
Rod