He was talking about on drops.
In a free fall situation you will fall with the ride vehicle. ToT is of course an exception, is it is accellerated downwards faster than 9.8 m/s^2, but in a normal drop situation you are not going to leave the ride vehicle unless you either push yourself away or the air resistance on your body is much greater than that on the ride vehicle (hence my little joke about deploying my drogue chute).
Yes, when going over hills, if you were decoupled from the ride vehicle, you would indeed continue to travel in a upwards directon, while the train falls before you due to the wheels on the track holding it to the track. In fact, you are not being pushed up by the seat, but rather the seat is being pulled down from under you. In the refrence frame of the track, there would be no forces acting upon you (aside from gravity) as you continued in a straight line (well parabolic arc due to gravity) and the train followed the track down away from you.