Stunning time-lapse video of the stars, mountaintop in Spain (video)

I really love this super-time-lapse videos/series of photos that people do. You’ve seen them – where they’re able to capture the Milky Way moving behind their subject. Just tremendous.
I’ve googled without much luck to see how they do this – meaning, how long of a setting do you need on a camera ...
Stunning time-lapse video of the stars, mountaintop in Spain (video)