My take and being totally optimistic is that she just was jamming to the music and her parents have enough sense to not allow her to watch freaking
hack and slash movies?
Knowing my luck, this is what any future kids would be like for me. I grew up on horror, so it took a lot to phase me in real life (When I was a
little older than this girl, as part of the scouts we did a "haunted" trail with "zombies" in the woods that would crawl out and try to scare us; I
now feel horrible for the one that crawled out next to me, because I stepped on their hand instead of running away in terror).
She probably likes the music; I'd be a tad bit creeped if she was doing it because the figure was moving.