I don't think you can learn to ride or train online.
I think you can supplement you actual horseman's education by watching lots of videos with a knowledgable horseperson pointing out nuances and what to watch for, but I don't think a degree in horsemanship from ANY online source is worth a whole lot, IMO.
As far as Monty Roberts goes, I read his book and found some good information in it, stuff that made sense to me and fit in with my own observations and notions of horse training. I think he overstates that "magic" of "join up" but at its core, it's a sound training principle. If he exagerated or misrepresented his personal life in the book, it doesn't make a rat's patootie worth of difference to me in terms of evaluating his training methods. If I judged horsepeople by their personal lives, let's just say I would have excluded a lot of remarkable trainers from my education.
I find him less agressively self promoting than either Parelli or Anderson, and therefore a little easier to take. Doesn't mean his training methods are better or worse, just that I find them more palatable.
If you seriously pursue an education as a horseman, you'll observe and possibly train with a LOT of different trainers. It's never necessary to "drink the Kool-Aid" and wholeheartedly immerse yourself in someone else's method permanently. You may immerse yourself short term for the purposes of learning, but it's almost always a case of taking away what works for you and leaving what doesn't.
So, should you study Monty Roberts' methods and learn from him? Absolutely. He has some interesting, worthwhile ideas.
However, I am not at all sure what's to be gained from enrolling in an online horse trainer's university. I think your money would be better spent working one on one with a trainer in person.
Just my .02