Nicholas explains that he is looking for the horse to look for the bit and stay in the trot in the position he asks for until he asks him for something else.  He rides him in a figure 8 or serpentine until he make a change of direction with the horse still reaching for the bit through the change of direction.  As he puts him in more of a frame he expects the horse to continue to wait for him and be responsive to the half halt.  He works in walk pirouettes and trot half pass, all the while requiring him to wait.