Keep the right arm loaded to bottom out past the ball
Rather than unloading the right arm immediately in the downswing, the speaker keeps it loaded longer. He wants the club to go into the ground after the ball, not behind it; when he just straightens the right arm he has to change it to strike the ground after impact, so keeping the arm loaded longer lets him 'rifle' the ball.
Channel: SagutoGolf
Watch official source at 5:13