Courtesy of NASA's supercomputers. Each second of the video is 98,540,145 years. Approximately.
Update: If it looks like the galaxy in the center of the video is "eating" other star clusters and small galaxies, that's because it is. Check out this article at Science Daily:
"The Milky Way is constantly gobbling up small galaxies and star clusters," said Ana Bonaca, a Yale graduate student and lead author of a study forthcoming in Astrophysical Journal Letters. "The more powerful gravity of our Milky Way pulls these objects apart and their stars then become part of the Milky Way itself."
So now you know.