NASA: 7 Minutes of Terror
The Entry, Descent, and Landing (EDL) or the Curiosity rover... which is coming up in just a few weeks now! NASA went for a technically interesting piece that played on the uncertainty of so many new techniques and the slim margin for error. Thrilling!
SpaceX: Dragon Highlight Reel
A rocking video with beautiful shots, many in time lapse, of the recent landmark mission to the ISS. Slick, powerful, and exciting. Also thrilling!
Hard to say who's done better here on the cool video front. :D