I love, love this video! It was done by Improve Everywhere http://improveverywhere.com/, and is not as fun as some of their others, like Star Wars Subway Car, or Who You Gonna Call? (which reenacts the opening scene of Ghostbusters in the New York Public Library), but it really is quite enjoyable. It pokes a bit of fun at the art world, but at the same time it makes people look differently at ordinary objects. The descriptions of the "art" (which include trash cans and cables) are priceless - it's worth pausing the video to read them.
My favorite part? When someone puts a red "sold" dot on "The Arriving and Departing Of the Train (Ongoing since 1932)".