Please don't initiate the downstroke by using the Left Knee. Use the Right Hip.
This guy demonstrates a good Backstroke Hip and and Shoulder Turn. The "MacDonald" school. However, you can easily see and test that when your Left knee initiates the Downstroke that the Right Shoulder moves outward. Hard to control. You see him struggling to keep the Right Shoulder under control.
Ok, not so bad for an Elbow Plane Swinger but whats the connection between the Left Knee and Right Shoulder. Not direct. When the Left Knee moves Left, the the Left Hip "Rotates" back which "Pulls" the Right Hip and Straightens the Right Leg. Bad. What happens to all that weight on the Right Leg? Ok, not so bad if you keep weight on the Right Leg during the Downstroke, but it doesn't "Drive" the Right Shoulder.
To "Drive the Right Shoulder" Downplane, use a "Right Knee Anchor" and initiate the Downstroke by moving the Right Hip.
But isn't the swing from the feet up both back and down? If that's the case- the L. knee comes in as a good No.2 in the weight shift motion I would believe (after the L. heel down). Am I wrong understanding it like this?