This is one of the nicest viral videos I’ve seen in a while, it’s racked up 1.6 million views in just one week.

The campaign titled ‘The Fun Theory‘ is a series of experiments that try to change peoples behaviour by injecting an element of fun into it.

The best video of the series called Piano Stairs, turns a set of subway steps into piano keys which make a sound whenever touched. The objective was to encourage more people to use the steps instead of the escalator. It succeeded by 66%.

There is some great behavioural insight here, shows how important entertainment value can be to consumers.

Other videos in the series included the 50ft deep dustbin:

and the soon to be released Empty Bottle Arcade!

The agency behind this is DDB.