The earth, seen from the International Space Station (ISS).
I think the source for most time lapse videos is the Bad Astronomy blog. He covers astronomy (of course), but also promotes science and the scientific method in general. He also debunks anti-vaccination and climate-change-denying stories. I think the cool space related time lapse videos are as a sort of cat videos for him: a relief from all the depressing news.
I also noticed that most time lapse videos are on Vimeo, not YouTube. The signal (high quality videos) to noise (cat videos) on Vimeo is much higher. The YouTube channel of the Canada Space Agency is however really interesting. In the last half year Chris Hadfield, a Canadian astronaut who is now commander of the ISS, has been making a name for himself by posting videos answering questions about the ISS and living in space (how do you go to the toilet in space, how do you clip your nails…). Here is a cool video showing what happens when you wring out a wet cloth in space:
It does make wonder though. We used to have grainy footage of some dudes on the moon. Now we have HD-video of a guy circling the earth at a height of 400 km (less than the distance between Zurich and Paris, or Paris and Amsterdam). Is that progress?