Since this is definitely a more visual Talk I suggest that you watch the video, I am not going to paste extracts from the Talk.
Keith Barry is testing the boundaries of human perception and showing how susceptible we are to trickery. It is an amusing video to watch and he does not, unfortunately, share his secrets. I was waiting the whole way through for him to explain exactly how you trick the human mind (so that I may apply it for mischief with my friends and family - nothing more, I promise) - alas, the explanation never came.
I suppose with the TED Talks you get used to these speakers explaining everything they're talking about, so maybe I got a little spoiled and started anticipating exactly what the nature of every single TED Talk apparently is. Or maybe not, whatever.
The obvious question you have after watching this video is "Is magic real? Was that real?". Well, I would argue that, no, 'magic' as the term usually implies (wizardry, witchcraft, spells and what-not) is not real. What is real is that humans are generally easy to fool. What is also real is that there are a few people who have studied and become quite attuned to human nature and behaviours, making it quite easy for them to 'read' people - and what you may learn is that reading someone's body language can quite often be akin to reading their thoughts.
I don't want to be one of those skeptics who says "there's a rational explanation for everything" - but there's a rational explanation for everything (even if it's a bit weird, or if most people are not privy to that explanation).
If you blindly accept everything you see (in the way you see it) as truth then all you will ever know is one side of the scenario - the side of your opinion. Optical illusions show quite clearly how we cannot always trust exactly what our eyes see (more like how our brain is interpreting the electrical signals coming from our eyes). Especially in this world where not everything is as it seems, we must be vigilant and wary. We must question everything and investigate the nature of every thing if we are to make accurate and unbiased conclusions.
Just because you don't know how something works doesn't mean it's somehow preter- or supernatural - it only means that you do not see or understand how hat thing works. So, watch the video if you haven't already and challenge yourself: do you fall into the trap of 'magic' because you are dazzled by wondrous displays, or do you consider all the possible ways that those feats could be achieved, always leaving a little room for something you have not yet considered?