Billboard for Magic Festival Actually Does a Magic Trick

Behold ad agency lg2's unusual out-of-home effort for the Quebec City Magic Festival. Pigeons fly out of a giant magician's hat set atop a downtown billboard. It's neat, though I imagine it leads to a fair number of stained windshields and T-shirts. Abraca . . . dammit, I hate when that happens! Some in the blogosphere are all agog and can't seem to figure out how the billboard works. In the video below, the client says, "Like any good magic festival, we never reveal our secrets."