It's a good overview, but it's missing a few things... there's no mention of pooled metal or allocated storage accounts where you own gold and have it stored for you. It's true that small bars are easier to forge, but there are industry systems, like London Good Delivery that provide audits and certification for them. The large industrial bars are hard to forge because they need to be uniform. Also Gold ETFs often have different underlying assets, sometimes they're invested in gold derivatives or futures (which is not necessarily bad, but economically different to direct gold ownership.)

Also it doesn't mention the firm I work for :-) BullionVault.com - we have over $650m of gold in our care and appear on CNBC regularly, so we're big enough to be worth a mention!