This video was just posted by the SFU Choir's YouTube channel. It's based on the xkcd comic, "Every Major's Terrible".
For more information, visit http://www.everymajorsterrible.com/
The song was sung by the SFU Choir, of which I am a member (http://www.sfuchoir.ca/), and written by Randall Munroe (http://www.xkcd.com). The video was produced by Samantha Derochie (http://www.phlyingwaylstudios.com/)