"The 'cult leader' in the video is Derren Brown. Brown is a master of a classic branch of stage magic called "Mentalism." You can find many excerpts from his performances on YouTube.

How did he do it? (Taken from suggestibility.org)

What's happening in the video? A lot of things. First, by the time we see him with his audience he has planted a lot of suggestions about his spiritual ability. They know before coming in that he claims to be able to impart a spiritual experience with just a touch. This is a pre-trance suggestion!

Then when he starts speaking his whole manner is calm and soothing and "safe." His voice in particular is calm and soothing and only very subtly modulated at all. He exudes "goodness" and "trustworthiness", which makes it easier for people to relax mentally, and to trust him. This is all trance inducing in many people and some of the people go into a light trance (mild dissociative state).

Which sounds pretty weird. He can put people into a "light trance" just by talking soothingly? This sounds a bit hard to accept because we place very strong esoteric connotations on the word "trance." However, recall that "trance" is just a form of dissociation, and you experience a mild state of dissociation yourself many times a day. And these dissociative episodes are very easily induced. Just watching TV, for example, will induce a mild dissociative state; you are dissociated (in a trance) whenever you become totally absorbed in the show.

Brown is now observing the audience and he notices that the woman in the front row is beginning to show symptoms of dissociation. He engages her in conversation, and then suddenly darts his hand close to her head. And because she is already well along this creates a cognitive overload and she goes into a trance. Brown has performed a "quick trance induction."

She then indeed has a spiritual experience because it has been previously suggested to her many times that Brown could give spiritual experiences to people. Also, when Brown asks "As skeptical?" this is a suggestion that she might not be. Other people hear her describe this experience and it reinforces the strength of Brown's carefully planted suggestions that he can give people spiritual experiences.

Then he takes a break and invites people who aren't buying all of this to leave if they want to. All he is doing is getting rid of the people who haven't proven to be susceptible to his methods. He doesn't want them around because their lack of acceptance might break the mood that he has carefully been building up.

Then he picks someone else whom he notices has been responding. He gets the man to stand up, face away, and close his eyes. Brown then plants the suggestion that the man will fall backwards. He plants this suggestion by saying "Don't worry about falling back, I'll catch you if that happens." Sure enough the guy falls back and has his own spiritual experience.

Which reinforces the suggestion in the rest of the audience that they might have a spiritual experience too! After that the thing just snowballs.

Pretty scary?

Brown has just demonstrated how extraordinarily easy it is to induce a spiritual experience in people and to convince them that you have extraordinary spiritual powers. If Brown had wanted to start a cult at that moment then some of those people might have ended up being his nucleus of adherents. Fortunately, Brown is just trying to demonstrate how frighteningly easy this sort of thing is.

But there are many social predators who have also developed such skills to a virtuoso level. These people also are experts at the other skills of mentalism described above.

Did you find it hugely unsettling that Brown had such an easy time "recruiting" these people? Good. You're beginning to get an appreciation of how frighteningly vulnerable normal human psychology is."