^^also agree with above.
It would be an understatement for me to say that I disagree with every sentence (well almost every sentence). Not only are some things very bias, but some of the technical facts are wrong (such as he says that your HSC mark is given to UAC, it is in fact your raw HSC mark, not your HSC mark; also the scaling of a subject is not really if a subject is hard or easy, its the quality of the candidates; maths and sciences are no easier to "benchmark" than humanities).
As many people, including UAC say, you should NOT choose your subjects based on scaling. Instead choose your subjects based on what you are interested in and what subjects may help you with your future study or work.
And remember the HSC is not about getting a UAI of 100. Imo, anything over 90 is excellent, and over 80 is an accomplishment too.