She is obviously reaching upwards; she's stretching. Why is she doing that? It's because she is trying to increase her height. She is on the ground, and the people in front of her are taller than she is. So, she needs more height, and she's reaching for it.
Now, if you watch the film, you'll see that she is mostly reaching up, and the waving she is doing is mostly with her hands. In other words, she is waving mainly from her wrists.
You can watch it yourself. It starts at the 20 second mark.
But, the other thing she is doing is arching her back, or you could say swaying her back. And that happened naturally because she lifted her arms straight up. She didn't raise them out to the side and then up. She raised them in front of her and then all the way up, and in the process she swayed her back automatically.
Also notice that her hands are spread far apart. They are not brought together.
But, how does her wave look in the Hughes film? Well, her hands are together.
You see that in one, her hands are brought together, right? And you see that in the other. her arms and her hands are far apart, right? On the right, she is not arching her back. On the left, she is. So obviously, it's not the same wave because it's not the same kind of wave.
And, we don't have to wonder about that because they have to be two different waves. The wave on the left from Dorman was done when she was facing Houston Street, but the wave on the right in Hughes was done when she was facing Elm. In Dorman, you can see that she is facing Houston Street, and in Hughes, you can see that she is facing the doorway. So, they have to be two different waves.
But, if she was going to wave twice in a very short period of time, is it likely that she would do it in two different ways?
No, it is not likely. It is very unlikely. That's because nobody thinks about how they are going to wave. They don't decide to wave this way or that way. They just spontaneously wave, and she would have done it the same way. Her biomechanical response, that is, her neuro-musculo-skeletal response would have been the same.
And when you look at her in the Hughes film, it looks very much like a computer-generated thing. It has a very basic quality and a perfect symmetry which defies reality. You'll notice in the gif below that we only see her arms already raised, and then we see them come down. But, I can tell you that the movement down is too slow. The movement down is powered mainly by one thing: gravity. You stop holding your arms up, and gravity takes them down. And that is especially true in a child because children are better at relaxing their muscles than adults are. And gravitational speed is faster than that.
But, I think it's interesting that both here and in the film when you watch it, her arms start by being already up. It looks exactly the same in the film. We don't see her lifting her arms. Why? I think it's because it would have been a much more difficult and complicated process to fake her arms going up and down. By starting with her arms already up, all they had to do was produce some frames in which her arms were coming down. That was the only motion needed. It would have been much harder to go both ways, up and down.
What we see in Hughes is fake. The reaction in Dorman is real. It looks genuine. It looks natural. The Hughes figure and the Hughes action look contrived and artificial. Her natural action we can see in Dorman. Everything about her in Dorman is real except for the sliver of pedestal:
The white pedestal is fake. Just more film fakery from the people who brought us the JFK assassination, the most image-altered event in the history of Mankind.