Occupy Wall Street. The Rich / Poor Divide. Fiat Money - YouTube This video is pretty informative and easy to understand; I've showed this to a couple people and they seem to understand fiat better.
It explains the functioning of fiat currency rather well, but I don't know that it fully elaborates on the role of central banks. Central banks print the currency as a debt bearing interest to nation states, ie. every single usd/gbp/euro/etc printed is a debt with interest owed to the central banks.
^ Govt uses force of law to make you accept paper currency with no inherit value other then faith in said government. This faith is abused throughout history time and time again, as the currency continuously loses value in the long term, encouraging the individual to borrow beyond their means rather then save their money.