Hour Physics: What makes a good (or bad) youtube science video

November 30 Colloquium at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario. Thanks to Neil Turok for inviting me to speak! also available at http://pirsa.org/displayFlash.php?id=11110110 http://www.perimeterinstitute.ca http://www.perimeterscholars.org Created by Henry Reich