What you're seeing is the evolution of scientific fame. The size of the scientists' names are determined by the frequency of their appearance in books published each year between 1850 and 2000. The names are color-coded by the year of their first appearance.
NOTE: If you want to see this at its most pretty (and legible), you should go HERE and change 360p (at the bottom of the video) to 720p HD. And then hit the full-screen button on the bottom-right corner. Let the video load, and enjoy!