The Chinese real estate market in general is very depressing: high prices, lots of uncertainty, no good bargains without buko guangxi. The smart money in China looks to a more stable/growing market to invest in, and the USA is very accessible. Its not necessarily all gray money (or even black money) feeding the buying, but there is probably some of that.
I'm sure there is some overseas participation in the San Francisco housing market. And San Francisco does have a high vacancy rate (relative to the U.S., per the 2010 census).
That's an interesting situation to try to understand. It's not an especially sound basis for an angry rant about corrupt foreigners ruining the housing market there.
The corrupt Chinese officials probably have more to do in ruining the housing market in China. They also have "retirement plans" that involve setting up their kids in a University/House abroad in some country without an extradition treaty (see http://en.wikipedia.org/wiki/Naked_official). But most of the money coming into the states from China is probably legitimate (or at least mostly legitimate, as much as can be said for the micro corruption that occurs).
Understood that he ranted, but Chinese monetary policy, along with the fact that the ultra-wealthy in China are often politically connected rather than talented founders, has certainly created a situation where tons of Chinese investment is buying up housing stock in any city which has seen a steep rise in prices.
