Those curving streaks are the flight paths of birds.
With a simple editing trick Dennis Hlynsky (a professor at RISD) turns an already beautiful flock of swallows into an amazing tangle of interwoven trails. Stick around until the end to see them dive in unison.
It’s Okay To Be Smart and Fast Company shared another one of these videos, and I ended up exploring the entire collection. Hlynsky’s created lots more videos like this — of birds, bugs, snow, fish, fighting ants — and they are all mesmerizing.
Here’s another one I like:
I want this as my screensaver. This is awesome.