The little girl has just realized that some of the horses are stationary. She'll figure out it has something to do with what is in the roof of the horse. I remember just when I figured it out. I was five years old so this was 1967 for me! Bless her little young heart.
I rode on these when I was a kid never knew there was an orchestrion making it’s music if your wondering it’s called a Wurlitzer 153 (I think) it’s a musical organ made for carousels
The Deer Lake carousel in Burnaby, BC, Canada has a calliope like that. I love the music it plays. And it also used to play Christmas carols in December, but I don't think they have those rolls anymore...