I saw that video a while back and I love the idea. It had me thinking about other ways to encourage stair use over escalators.
I engaged in a lengthy mental foray during which I explored the possibility of making escalators dependent on power generated by stair use. (there are technologies that capture the kinetic energy of a footfall on a surface - in fact, that step piano uses similar tech to register the key strikes).
The result I ended up with was general public outrage.
It might be cool (if you had the funding) to get a troupe of people at the top of a public stairway (that was adjacent to an escalator, like in the video) handing out something nice like gum or something to people who opted for the stairs.
Hey, you could get the gum company to pay for it :)