Here is a still shot of Ligety. I have annotated the physical characteristics that indicate that he has set up forces on the new outside ski that use the external forces acting on him to drive his ski into the turn. As Ligety approaches the apex of his extension, he is moving forward in the hips and moving the Centre of Pressure to the ball of his foot. This sets up an over-centre mechanism that drives his ski into the turn in multiple planes. As soon as the over-centre mechanism begins to engage Ligety pivots the ski and completes his extension. This timing of these two events and the use of momentum to extend against reinforces the external forces that are driving the ski into the turn. While the NY Times video shows this quite well, it does not show the multi-plane torque forces at work. I will explain these in detail in a future post. While Shiffrin makes a similar move she does not maximize the use of extension the same way Ligety does.