The feed seemed live. Channel flicking between BBC1 and Channel 4 gave the impression that there was a live feed from both channels.
He couldn't reveal the balls until after the Lottery reveal due to Camelot rules and regulations which are in place to stop people from cheating the system.
It seems real, but Derren Brown is a tricksy fellow. It could be like that Horse-Racing bet he did with the hundreds of people, but only showed film of the winner.