Tom Palmer of the Atlas Network has a very concise -- yet quite devastating -- video exposing the Keynesian fallacy that the destruction of wealth by calamities such as earthquakes or terrorism is good for economic growth. Tom cites the work of Bastiat, who sagely observed that, "There is only one difference between a bad economist and a good one: the bad economist confines himself to the visible effect; the good economist takes into account both the effect that can be seen and those effects that must be foreseen." As you can see from the video, many who pontificate about economic matters today miss this essential insight.
I can't resist the opportunity to also plug a couple of my own videos that touch on the same issues. Here's one on Keynesian economics, one on the failure of Obama's faux stimulus, and another on the policies that actually promote prosperity.