Starlings are really obnoxious birds. Never really liked them much. They're noisy. Mean. Messy and generally a nuisance. But when they flock together like this, it's truly a wonder to behold.
Direct link if you can't see the video.]
I witnessed something very similar to this once when I was walking in the meadows around lovely downtown Northampton. I was mesmerized for a very long time before they settled down as the sun finally set. It's not something you ever forget.