The point initiates the secondary by bringing the ball up and swinging it to the trailer (4). The trailer swings it to the backside wing. As the ball is being reversed, the point cuts hard across the lane and comes out on the ball side corner/low wing. The wing swings it to the point guard.
(Note: In the clip both wings start on the same side, opposite the point guard. I think that was a mistake and the 2 cleared out to balance the floor.)