It probably won't shock you that the most popular YouTube video in the past month was "Gentleman," the latest hit from South Korean rapper PSY, whose "Gangnam Style" is the most-watched video of all time. More surprising: among the other most-watched videos was an advertisement for bottled water. Evian's baby&me features several adults dancing with toddler versions of themselves in the reflection of a store window. Only at the end of the 77-second video do we see a bottle of Evian, along with the slogan "Live young." Since its release in April, the video has garnered more than 53 million YouTube views. By contrast, Nestle's self-explanatory "From Maine Water Springs to You: The Journey of Poland Springs Water" has barely cracked 500 views. So why did one water commercial sparkle on YouTube, while the other fizzled?