Marginal pricing is a long-term phenomenon that happens after the original entrepreneur has made “above-average” profits for a period of time, before that profit is competed away. That service will not be profitable anymore, but you can bet that the entrepreneur will then invent some add-on product that will make some more “above-average” profit, and the cycle continues. Nobody will stay in business for too long if they make no money above marginal cost, simply because of the opportunity cost of their time employed in a more profitable endeavor.
Marginal pricing most often comes into play when a business is declining, or on the verge of bankruptcy. It also factors big in the mining, and oil & gas industries. When deciding whether to begin production, the developers have to consider the long-run average cost — with a good profit margin factored in. Once all the capital costs become sunk costs — future decisions about whether or not to continue production pivot around the marginal costs of production, compared to marginal revenue.
Clearly, Anderson is playing to the Starbucks and cocktail party crowd. He has a knack for making dry as dust economics sound quite cool — but, in so doing, he does oversimplify. You could quote Anderson at a coctail party & be considered trendy -- if you go deeper, eyes begin to glaze over.
To say the Internet is free, however, is absurd. When Al Gore said he “invented” the Internet, what he really means is that he created the tax that appears on your phone bill ever month. Clearly, it is not free.