How much internet usage does watching NBA all star saturday night live streaming on yahoo sports?

I have a 6gb optus broadband and I'm afraid i would use a lot from watching live streams pls hellppp. There's no free tv coverage of the NBA allstar here in australia it succkkkkssss gddmmt!!!!!|||a decent movie that is an hour and a half long is 600-700 mb. if you're watching for more than 4 hours i would start panicking then. but for now, no.