Here's another Darren Brown video. This time, the subliminal message is more subtle. Watch and see if you notice it/them.
I suppose you did not.
If you do not want to see how subliminal message was conveyed, don't read the rest.
Really, seriously, if you do not watch the video before you read this, the video will be much less interesting for you.
So, the Irish girl is given the subliminal message at aproximately 22-23 seconds into the video. As DB pulls her out of the crowd he says rather indistinctly and rapidly "right leg up" right after he says "come up here with me."
The girl obviously did not recognize that she had heard the message then, but she did hear it, which is how DB was able to "predict" her movement. She did recognize that the thought was not her own, which is interesting.
The message for the second girl is a little less clear. It may have been edited out - the audio seems to jump from "can you take your bag off" and "and again your hat" it may be that the actual message has been edited out.
There is, however, another possible answer, which is that she is simply adopting what she hears from the young man behind her. In other words, DB may be using a slightly different technique here, in which the person's own thought is supplanted by the subliminal suggestion.
With the third guy, the subliminal messages are mostly visual. DB makes repeated guestures to his own head, and even has the young man put his fingers in his ears. Nevertheless, fingers in the ears still permits some barely audible sound through, which - combined with DB himself practically demonstrating how to make the guesture at 3:05 and again at 3:07, and then finally to tell the young man to unstop his ears.
For the crowd, the subliminal message is both DB's own gestures, as well as the reinforcing image of the young man behind DB. Notice that the young man is taller, so the young man's hands appear to be on DB's head.
This mostly just goes to show how predictable and susceptible to cause and effect humans are, even when they think they are exercising their so-called "free will."
Now, I am not discounting the possibility that spiritual forces are at play - I simply don't know. There seem to be fairly reasonable physical explanations for many of the tricks that DB plays - and yet the human mind is not completely physical.
Regardless, though, this video fairly transparently demonstrates the fact that the human will is subject to the laws of cause and effect. That's not surprising: everything but God Himself is subject to such laws. God is the only uncaused cause: not man, not angels, not demons, and nothing else in the created order.
P.S. Word of caution: DB is opposed to Christianity. In some of his other videos he demonstrates how he can perform the Benny Hinn-style "slaying with the spirit" miracles, and how he can convince people to believe in "god." DB is, of course, unable to do the dramatic miracles that Christ and the Apostles did such as healing lepers, curing men born blind, making cripples walk, or raising the dead: the kind of miracles that ceased with the completion of Scripture.
(Hat Tip to Machaira for the name of that Christianity-embarassing televangelist.)