Exactly, Rick H.
Carl thinks he's skiing neither pronated nor supinated, but rather neutral, but if he's skiing properly balanced and countered that's likely not the case. Subtalar neutral doesn't happen until the weight is way up on the ball of the foot, and the heel is about to lift. Not how you generally want to stand on your foot through the duration of a turn. Pronation/supination are not as much about if you're trying to tip your feet inside the ski boot or not, as they are about how where you're balanced along the fore/aft plane of the bottom of the foot, and the rotational state you're assuming, and how the foot responds in accordance. Carl's counter and centered fore/aft balance in his video suggests his outside foot is actually pronated.
Carl, your understanding of this stuff would better mature if you referred to the foot tipping inside the boots you're talking about as inversion/eversion, as Rick H. suggests, and then study pronation/supination in the greater detail it encompasses.