Not sure on the shadows, but the movements don't look perfectly in sync to me. That may be an illusion in itself. They just aren't timed right. First thing I noticed and thought of.looks fake to me, I see 2 sets of hands moving things differently. They don't look in sync to me, and also there are shadows on the hands in the top portion and no shadows below.
While the video was really cool to watch, some of the other stuff this guy has done is even more impressive. Thanks for sharing that source website!