How do figure skaters exploit Newtonian physics when they spin?

Legendary MIT physics professor Walter Lewin describes some of the science that was in action during the Winter Olympics in Sochi. He explains how ice-skaters use their arms to moderate their moment of inertia, which in turn affects the angular velocity of their spins. The biomechanics is fairly straightforward, but Walter Lewin always manages to make his lessons engaging thanks to his trademark charisma.