From my ultra-conservative point of view, the presentation is based on popular but anyway incorrect assumption about the nature of money. IMO, money are backed by power, by rude power of repressions that will make you unhappy if you're unable to give some amount of money to some _powerful_ authority. No promise of repressions (or no understaning that the danger is real) means no money. As a consequence, money does not work for relations that can't be enforced.
Reputation currencies? Ok, I have some reputation for sale, Mr. X has none but would like to get one. Will you really trust him (and stop trusting me) if we swap reputation values?