Nope the narrator is correct the turbulence slick is upwind (as the boat s-l-o-w-l-y drifts 'downwind' due to the pressure on the sail(s)). The slick is between the boat and the oncoming (breaking) waves, and causing them to break 'before' they get to the boat.
If the slick was in the lee of the main, the waves would break 'after' hitting the boat !!! ;-)