The guy shook. This was not planned, I'd bet. He looked on for a few minutes, trying to get his composure back. He put the gun to his head one last time, to find nothing, before firing the bullet away from him, correctly this time.
Not your usual Sunday evening television, I guess.
This stunt has obviously caught people's imagination: his website, derrenbrown.co.uk, is ironically dead from too many people trying to access it, I bet.