Walter Block met Rothbard in 1966. Here, Block tells a joke making the point that antitrust law is dead from the neck up.
There is nothing wrong with a monopoly price. Whatever price the free market establishes will be the best price. There exists an unfortunate illusion about monopoly price. Labor unions, by exacting higher wage rates, do achieve identifiable restrictionist prices for their members, but only at the expense of lowering the wage rates of of all other workers in the economy.
Patents are grants of exclusive monopoly privilege by the State and are invasive of property rights on the market. A copyright is a logical attribute of property right on the free market.
An Alice J. Lillie Seminar. This lecture covers pp. 629-753 in the Scholar's Edition of Rothbard's Man, Economy, and State.