What Starts the Down Swing?
Technically, yes, the lower body starts the down swing. There is a common fault that plagues a lot of golfers in that they force the lower body to start the down swing which creates a mismatch in what the body and club are doing.
Jon demonstrates how to create a connection in what the body is doing and what the club is doing. This is going to create more power at impact as opposed to using all that energy by forcing the lower body to fire.