I didn't know we were taking in consideration doomsday events when contemplating investment ideas....
Since 1970 gold has increase in value by 3200% Since 1970 the Dow Jones Index has increased in value by 1200% (not including dividends)Since 1970 real estate in the US has increased by 1000%Your comment doesn't match with reality.The above chart shows that the DOW has been in a bear market with respect to gold for the past 10 years, going by the trend the DOW will be in a bear market for the next 10 years or so.
This is a far fetched scenario. In you example there would probably be no exchange as the entire economy contains just two people and two goods, therefore no need for a currency. In a real economy like in the video, what happens when the currency system fails is that an alternate currency is used, and for some reason people always return to gold as something that has some sort of value and can be trusted.