Gonzo is correct here. Barbecue is a method of cooking by indirect heat in the smoke of a wood fire. What we commonly call smoking. Anything cooked over direct heat is grilled.
Barbecue - Wikipedia, the free encyclopedia
In all due respect to our friends Down Under most of the cookers depicted were really grills for cooking over direct heat. Nothing wrong with that, but in the South that is not barbecue.
Texas for brisket, Memphis for ribs, East Carolina for whole pig, Tenn Ala Ga for pulled pork. Now that's barbecue cooked long and at low temps.