neat trick but kinda simple, one of the hands that were holding here head were fake, notice how she never really moves them once she has put them together shes holding the fake one with the real one, and you can kinda see her pulling her arm out after she puts them together, the shoulders are probably a small frame to give it the shape that she is holding with her free arm, and you can even see her moving her arm inside the dress, after she gets back up.
but still a really good trick