Someone I talked to about this made the point that the numbers Reuters cited were probably by a factor 1000 too high (given typical oil purity vs implicitly claimed purity of the 31 million tonnes ore to produce 320 000 tonnes gold). I guess this video sources those same figures.
This sounds right.
@Snuskpelle
320,000,000 tons x ~55,000,000 $/ton = $17,600,000,000,000,000 ($18 QUADRILLION) which is not the value claimed. So, he can't mean 320,000,000 tons of pure gold and must mean 320,000,000 tons of material prior to refining.
Dividing 18 quadrillion by ~1000 gives ~$18 trillion, or the roughly $12 trillion being claimed (close enough for an orders of magnitude approximation). So, the claim must be for 320,000 tons of pure gold after being refined, not 320 million.
(Not sure why Snuskpelle divides by 100 but I'm guessing that was just a mistake.)
So, the claim is they believe there are deposits equivalent to 0.13% of all existing gold.