Skip Blumberg, Artist in Residence at the 1989 VideoFest and observer of the extraordinary, has once again come up with a little preciosity. On„LoBro" (Lower Broadway) in Soho he happened to meet a street performer with a virtuoso percussion act based on some pretty unusual bits and pieces. Blumberg has his camcorder at the ready, shoots, interviews captivated passers-by - until the fuzz show up and expose themselves yet again as standard representatives of the species. The law's the law, even if it spoils the fun.A shame really, as life is never a bowl of roses at the best of times. Four minutes cover a lot of ground.