Volkswagen Musical Stair Case in Sweden

I saw this on Richard Wiseman's Twitter Feed:

It's a viral ad for Volkswagen, at the "Odenplan" station in Sweden, posted on this site, with this commentary (via Google translate):

"Take the stairs instead of escalators or elevator and feel better" is something you often hear or maybe read in Sunday attachments. Few if any people have followed this advice. Can we get more people to take the stairs over the escalator on a normal day in Stockholm, by making it more fun to take the stairs? The result you see here.

It is certainly plausible and looks real, and on The Daily Mail site, I saw install photos from K J Vogelius, which led me to this "making of" video (which had 70 views when I found it):

Photos from Mr. Vogelius' flickr stream:

The technical details are a bit fuzzy from the video, but there are lots of ways to accomplish this today.