'Just' a comment

I recently watched Radiohead's 'Just' video. Even though the damn thing was made back in 1995, it still creeps me out. A man lying on the street, for no apparent reason. He refuses to explain himself, and when he does, everyone around him immediately lays down on the street as well. What did the guy say? What could make people react that way? I shiver trying to come up with an answer. It's been 11 years and I still haven't found it.