A hand tilts a bottle of ketchup and, instead of staying where it is until it's shaken, the ketchup easily slides out, leaving the bottle clean. That's according to CNN, which reports that the 20-second clip was viewed more than 125,000 times on YouTube. That's not what mechanical engineering students at MIT had in mind when they developed LiquiGlide. Are viral videos always accidents? Can producers study the data and deduce techniques for making it happen? Those are questions asked by John Seabrook, who wrote a lengthy piece for the New Yorker called, "Streaming Dreams: YouTube Turns Pro."