Sadly, I cannot find an embeddable version of the scene, nor the scene in one piece, but part one is here, followed by part two here.
I watched The Red Shoes (1948) last week and loved it, but the ballet scene in the middle, an adaptation of the Hans Christian Andersen fairy tale "The Red Shoes," stood out to me the most. Not only does it fit perfectly within the main story of the film, but it stands well on its own. I know absolutely nothing about ballet, but to me it looks like a wonderfully gorgeous, colorful, and fabulously danced piece, with the perfect atmospheric music to match. I also loved that it also managed to be slightly creepy (thank you, weird shoemaker).
So worth watching on its own, but even better if you watch the whole movie along with it.