Wow, that's some really creative stuff going on there and beats any prank I've seen in America or anywhere else for that matter. To answer the question though I would be initially like what's going on but then I'd try to understand it there was something more to it and wonder if it was a prank.
This one looks better than the American version because of how they pulled the special effects together. That's besides the point, if I saw this happened I would first look for cameras to see who was recording this prank, short of that I wouldn't leave but would want to see more!
You probably already know my reaction right? My first action will be to step aside and look at it as a show just as I would a live show. I will look at the people's faces and how they are reacting to it, then when they are done I would resume getting my food because by then I would probably be even more hungry.