Maybe it's just because babies are always cute and fun to watch. The technology used is not new, although the production values of this clip makes it almost believable. And this is not the first time we've seen dancing babies.
But somehow the big idea, executed well and stemming from a solid strategy, connects with its audience. I don't know how long ago this was done, but I still find it relevant. Reminds me of how unexpectedly (or as expected), the Bulilit ad for Camella Homes also spread like wildfire.
Great strategy & insight. Good execution. Cute and entertaining. The formula for a good ad. Always.