It definitely was a fair ball. If you look carefully, there are two vertical poles with a screen in the middle. The right most pole is the foul pole and the left pole is there just to support the screen between the two pole. The screen is there to aid the umpire in viewing a foul vs fair ball. The ball clearly passes behind the two poles, but is visible through the screen as it passes behind the screen.
They showed this in slow motion repeatedly. The umpires went to their dressing room to review the TV replay. They came out and signaled a home run. The two idiot AU announcers went crazy. They went on and on about the call the rest of the game. The fans kept yelling "home run" every time we fouled a ball into the first base side stands.
TV replay also showed that a runner, Willhite, we had thrown out at home was safe. Even the AU announcers agreed with that.