Seriously cool stuff. From the Vimeo page:
We see galaxies in the sky, but cannot see the dark matter clumps surrounding them. However, we can simulate them as they form in a model Universe. In this video we show how good the agreement is between the observed distribution of galaxies in the SDSS sky survey, and the predicted distribution of model galaxies associated with dark matter halos in the Bolshoi simulation. It's hard to tell them apart!