I thought it was a split frame thing too, but then noticed that they veer into the tens place pretty frequently and cast shadows. :) (And the other comments give more details about the original art installation.)
That's not to say that you couldn't do a split-frame thing like this, with a little bit of cleverness and planning. Even if it were only split around the middle, that's only 72 transitions to film, which isn't too bad.
EDIT: Actually, the lighting would be really difficult if it was a trick so I'm going to say it's real.