A little bit of context around the "skit" for those who won't otherwise get the context. Its occured in a show that has been off the air for 20 years, something like a Johnny Carson kind of variety show that has different segements. One of the segemnets is called "Red Faces" and it is where amatuer performers got up and did little acts to be judged by a panel of judges. The show is now doing some reunion specials and this act was actually one that was performed 20 years ago on the show so it was a reunion for the performers.
Now its also worth noting that the performers themselves are not "white", but from a variety of ethnic backgrounds, mostly from the sub-continent I understand. Its also worth noting that "blackface" doesn't have the same history in Australia that it does in the US.
That said, its extremely poor judgement in my view to have run the skit. That said, I don't think it was motivated by racism, but just poor judgement. I generally don't think you can call something racist by reference to it being offensive to a foreign culture. Not exactly the same, but its like saying that I am being offensive by allowing my girlfirend to wear a tshirt because that would be offensive in Saudi Arabia. Australia doesn't have the same history that the US does. That said, US history is not unknown in Australia and I fail to see how the producers and performers could have not seen the potential trouble that a skit like this could have caused (even if it was originally done some 20 years ago).
Whether Australians are racist is a far more general question, but one at which the answer must undoubtably be "some of them are".