"'I'd qualify that by saying that speculators can create incentives for other people to hold physical product off the market, if they drive the futures price well above the spot price. But that hasn't happened.'
How does he know whether product is being held off the market? He doesn't cite any sources, and even if he did could they be trusted?"

Oh come on, give him a break! He tells you that what hasn't happened is futures price being driven well above the spot price. And he does cite sources -in fact he provides you with the graph comparing futures and spot over time (another way to look at it would be Jérôme's graph -futures are like spot, only a little bit lower).

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi