Rainman then
You claim that Derren Brown possess capabilities that enable him to "know instinctively where the cards are", meaning each and every card as it is coming out of the shoe, while also"adjusting his map for dealer-driven randomness", which you say "would be simple". Alright, this can be done theoretically, but I have not witnessed it first hand, and I haven't had a reliable testimony from someone who witnessed such a thing first hand, so I cannot but reserve judgement until such time as I have some evidence beyond simple claims. In the meantime, I remain highly sceptical as to the ability of someone to "win at will", even when he knows every card coming out -- remember that Brown was not heads up!
Once more, I point out the wholly different explanation provided by Derren Brown himself, about his winning technique in blackjack, Brown who is not selling voodoo and is usually quite forthcoming about what he can and what he cannot do.