The Austrian theory offers some important insights and a lot of it's ideas are valuable. That is why it is widely considered a precursor of modern credit cycle theory, but carrying it's conclusions too far without considering other factors such as savings rates, fiscal and monetary policy.
No need to take his word for it. If you look at the Austrian school theories you'll see that those things aren't accounted for. Another crucial element that isn't considered is velocity of money, and the concomitant effects on money supply. The Austrian school has a lot of important insights, but it omits several important factors. It has a good and useful set of ideas, but it's not the grand unified theory of economics that many libertarians (like me) wish it were.
Well, I just responded to your other post, where you were economically confused :)
Velocity of money? Concomitant effects, huh? .. I suspect you might be some sort of government shill though. Very few actual Libertarians don't see Austrian economics for the rational truth it is.
You're not going to take my word it, but feel free to see for yourself. Watch their lectures on YouTube ("misesmedia"), and you'll get it.