http://www.youtube.com/watch?feature=player_detailpage&v=HfAx2aGyBGY#t=235s
He did so previously as mentioned in this press forum: https://bitcointalksearch.org/topic/2012-05-28-brotherjohnf-silver-update-52812-capital-controls-video-84252 ("2012-05-28 BrotherJohnF - Silver Update 5/28/12 Capital Controls (video)")
The question of the day was something about a local barter currency ("TEM") somewhere in Greece.
Here's some of what he said:
[...]
Let's say someone offers a haircut. The network determines that's worth 10 credits. Ok, there's the big flaw of these sorts of things here: you do not want to have the network determining what something is worth. Is every haircut equal? What if someone is really poor is giving haircuts? What if someone is really good? So, that's a big flaw to have these assigned prices.
You have to have a free market. [...] You can't have this centrally planned economy like this, it just simply wont work and the pricing mechanism will be broken. [...]
It's an interesting concept [that greek barter currency], it definitely needs some work. It needs to borrow some of the ideas from bitcoin, with a limit on the number that's locked in and some kind of anti-counterfeiting mechnism built into it. If that's not there, then you're totally at the mercy of the people who administer it and you can see what's happened with the federal reserve and how that's worked out.