Derren Brown takes on 9 chess players simultaneously

The video is out of sync with the audio. ARRRRRRRRRRRGGGGGGGJHHHHHHHH

How did he predict the numbers at the end?

He didn't. He stopped the game there. When his opponent had the number he wrote.

He wrote the thing on the big board and remembered them. The thing in the envelope was probably written down as well and handed to him. When he walked up to reveal it, he revealed that piece of paper rather than the other one.

The video is synched extremely poorly to the audio. Distracting. The concept is pretty awesome, though.

Unless he had a grandmaster or computer program signalling moves for that one game.

I didn't understand this the first time I watched it and I still don't.

Surely once Derren has copied the move played by player 5 on player 1's board he would have to wait by player 1's board in order to see the response to play on player 5's board.  But player 1 may not make the move immediately so Derren would not know what do play when he comes back to player 5.

I am pretty sure he just paid the student to lose the game, nothing else makes any sense.

dude, he goes to table 1 for an opening and does not respond. He the goes to table 2, 3 & 4 for the same thing. At table 5 he plays white so he mirrors the opening from table 1. He waits for table 5's response and remember that. He then does that with table 6, 7 & 8. Back to table 1 he mirrors the response from table 5 and wait for the response. It's Derren who doesn't respond each time, not the players. As for table 9, unless Derren is really good at chess, I think there's some tricks going on.

The problem is that the player is not obliged to make his move immediately. I have played in chess simuls before and the convention is for players to wait until the master returns to his board before moving.

The only way this can work is for Brown to alter the way the simuls usually run and he will be obliged to skip making moves a lot so he can move round to see what move the opponent has played. It would seem very wierd to experienced players.

oh, that case, I guess Brown just altered the way it usually worked. I have never played with masters so I don't know the convention.

But since this is a special even for the masters, I guess they won't mind :)