Gold was criminalized for use in transactions in 1933 by executive order. I think that's a fair point to mark the end of the "gold standard" and the beginning of the fiat era. It is true the US government would redeem dollars for gold for foreign countries up to 1970 or so, under Nixon... but indie the USA, it was a crime to use gold as money. (Though jewelry was allowed) up until the 1970s.

He's using the term "counterfeiting" in the economic sense.

One of the things that makes something money in economics is that it is difficult to duplicate, so you can't just make more of it for yourself. Fiat currency doesn't have that restraint. So, we can say it is not money, or we can say that it is being counterfeited. This is not a word chosen for its alarm value, though it should make you alarmed.