I'm not sure what show they're filming this for (20/20 or Primetime?), but I think it is pretty awful to make very young children "act out" the part of an abandoned child (so as to test the response of passersby. Very exploitative. Just wrong, emotionally and otherwise.
Plus, they sit in the same location so that one person tells their friends and they they go by and "punk" the producers. This is called journalism?