The episode is Foot Position Test: Breaking Diane
From the episode description:
Many of us have to turn our feet out a bunch in order to get to full depth.  While this is clearly functional, it’s not optimal.  If you are having to spin your feet much past 15 degrees, chances are you are compensating for poor motor control, missing internal hip rotation, a tight anterior chain (quads, etc.), and stiff ankles.  The further out your feet go, the less effective your hip rotators are at resisting the valgus forces created by the body (read: knees in).  Somewhere between 5-12 degrees is sort of a magic area where you can still get to depth and create freakish amounts of torque.