He does nail market-oriented views on the issue of risk; we don't have a good explanation of why private insurance markets do not function better. But since single-payer national health insurance violates every economic law known to mankind, I am again unsure how I could leap on the Democratic bandwagon.
Even leaving aside the empirical evidence, including our very own Medicare program, which demonstrates that single payer systems and variants work quite well, I think we understand quite well why private insurance markets don't work very well.
Adverse selection is enough for there to be complete market failure in an insurance market. The legal/institutional framework which gives us group health plans offset the market-destroying impacts of adverse selection for a time, but the proliferation of choice for employees has brought it back. Simple version: only the sick buy the "best" insurance, making the best insurance more expensive, etc...
I do think it's wrong to entirely think about health insurance strictly within the context of typical insurance markets. Most people really just have a "health care services delivery package" that they've bought with some catastrophic insurance tacked onto it.
But, either way, one can think of quite a few reasons why the markets for health care and health insurance aren't like "other markets," that is where the basic assumptions necessary for well functioning markets aren't satisfied. Adverse selection, imperfect information, lack of price transparency, etc...