Fire the trail arm from bent to straight through impact
To create clubhead speed the coach describes letting the trail arm go from bent to straight while keeping the trail wrist cupped and pushing down, firing from a circle just outside the trail foot at the takeaway to a second circle just outside the lead foot in the follow-through. He calls this a gear effect and says it is how the speed is created.
Channel: stayhandsy
Watch official source at 1:53Why this context matters
References a 'two circles' concept established in the coach's earlier videos.