A lot of Australians download American television because otherwise we have to wait six months or more. I used to think this was all a kind of conspiracy on the American side, but I have since formulated a theory that puts the blame on the Australian side. See, if you want to get television stations to buy Australian content even though the American brand is more popular, you have to lower demand for the American content. One way to do that would be to put a delay on imports so that the super-keen fans turn to the Internet instead. Then, by the time the shows arrive on Australian shores, the target audience has already moved on, and the only fresh thing to offer them is Australian shows.
Mokalus of Borg
PS - The problem with the theory is that this was going on before BitTorrent.
PPS - Parts of it might still make a valid explanation, though.