Read grip-end direction at the top to predict your path
The direction the grip end of the club points at the top of the backswing is the direction you tend to come down. With the grip pointing down, the plane flattens very quickly. When the left arm and shaft are in one line so the grip points into a vertical wall over the ball, most players follow that line down and out - over the top.
Channel: CraigHansonGolf
Watch official source at 3:44Why this context matters
Hanson is contrasting two top-of-swing looks in a lesson on flattening the downswing plane.