Is this the company based out of New Zealand? There are several "Guitar Mastery" sites, it's scary.
If it is, I watched the testimonial video on their website just to see if I saw any familiar faces. There is one guy on the testimonial who is currently posting himself playing over jam tracks on @MikeS Facebook group "Blues Guitar Unleashed Students," on a pretty regular basis.
If it's the guy I'm thinking of, he must also be a Griff student because everything he posts is from one of Griff's courses.