Actually, the person the book and movie were referring to was Buck Brannaman, NOT Monty Roberts. Buck was even a consultant on the movie, and they used one of his personal horses for a scene that the stunt horse kept getting wrong.
I like Buck. His no nonsense style and plain talk appeal to me.
A lot of wannabee american cowboys jumped into bed with Monty and sucked it all in - these had to be all very amateur and gullible people as the average experienced UK horsepeople were pissed off that some american thought we needed to learn how to break horses without cruelty when our own non cruel methods had been successful for hundreds of years.