Part of PONIES: The Anthology V https://youtu.be/Z0LgI6nF0rM

Source video:
My Little Pony: Friendship is Magic (S4 E5 "Flight to the Finish")

Source audio:
My Little Pony: Friendship is Magic (S4 E5 "Flight to the Finish")
"Rakuen (Requiem)" by Yoko Kanno