I looked at that thing too. I think you are better off working with someone face to face, watching DVDs and reading books. That certification has to be updated... you have to pay a fee to keep it, you have to have so many hours of "clinics" caught on video or recorded and send it into them and, you have to train horses to 'their' liking (I would imagine).
No one in my family knows horses either. But that I think, is just a rip-off. That is why I wouldn't pay thousands of $$$ to become a 'so-and-so' certified trainer, as you could only train 'their' way. When I can take advice from other trainers, friends, this forum, and either take it or leave it. My choice =)
Also, the best ways to learn are from a good horse. I would buy a solid, well-trained horse, for whatever it is you want to do, and let the horse teach you. Not only do you have to become a 'trainer' but a very good rider, and a leader, and a teacher.
You should always follow your dreams. And you can take the courses, but I just didn't like the set-up. And, you would need a horse or horses that could perform the tasks asked of you, which, I imagine some would be very advanced manuevers.
Lettin' the cat outta the bag is a whole lot easier than puttin' it back. -- Unkown