Many of my friends have shared this on facebook (and the Science Friday Video podcast is part of my iTunes feed!)
I can tell you from personal experience, it is just as amazing as the video. When I lived on St. Croix, I saw several octopii while snorkeling. They would be totally invisible until I was right on top of them. Suddenly, they would spring into view and swim away. I was lucky enough that I never go inked!