All I know is that Tommy Armour said to swing down and out on every shot including the driver. He also said go back count 1, 2, pause at top, 3 swing down.
It's NOT the same swing. The video covers basic set up but nothing on 1 piece take away, keeping elbow in or swing path. With the irons you should have a more verticle approach so your hitting a desending shot so your hitting down on the ball. The driver (just by shear length) is a more horizontal & your sweeping it. I liked the body axis thing in the video.