You should have noticed in frame 5 of the movie that only one plate of the capacitor is being charged positively. The other plate is "grounded." The right-hand plate and the left-hand plate are separated by only one-half of a turn of the dial. How can we claim this set-up is actually a capacitor and thus has equal and opposite excess charges on both plates? Hint: What happens immediately after the first plate is charged? Is induction possible?