Watched the segment the RE Agent Edwin said in Parramatta prices had come back 8-15% and in some areas of Sydney asking prices had come down 20%. Note: asking prices aren't prices.
I live on the West Coast and know nothing regarding NSW real estate and even I know Parramatta isn't a desirable area and its in the flight path of Sydney Airport.
The least desirable areas are the ones that will come down first. They'll be prone to the biggest swings in a frothy market too, if that's what some consider we've been experiencing. Quality never goes out of fashion.