Danger, danger, illusionist alert! Derren Brown is a 'mentalist', that is he performs illusions under the guise of mental tricks, psychology, the power of the mind etc. In reality this is just a guise, and when for example his professed method is hypnosis, it probably isn't, and instead misderection, slight of hand, gimmicks etc are involved. It's just another way to wow the public, and the public loves to believe it. Read '13 Steps to Mentalism' by Corrinda, it is one of the classic texts on mentalism and will get you wise to a lot of this stuff. That said, Derren is one of the masters in this field...