I think I agree with you if you are saying that a swing should have 2 pivot points - back hip and then front hip. The girl is only using one pivot point so the hips are turning but the front hip is not active so there is no stretching of muscles as the pivot point moves from back to front that would increase the speed of the swing. The boy in the walk up drill is doing it really well. Watch his legs.
That is an interesting way of saying it. Basically, what I see, is a rear hip that wants to do all the right things, but its progress is being impeded by a front side that is locked down. Overall this hitter has a great deal of potential, IMO.