I think you're confusing his use of the term "more responsive to pure demand" with "better responsive to pure demand," Mark. You're example is separate from what he's saying, and actually kind of demonstrates it in a backwards kind of way. When cable was a monopoly, the supply curve didn't really shift all that much -- sure, ESPN would jack their rates and thus increase programming costs, but much of cable's costs are fixed. As a monopoly producer, they were free to set artificially high costs and get away with it. The only thing which would affect their pricing decision was a shift in the demand curve. People wanted more TV, cable raised its price. If there would have been a large decrease in demand, cable would have had to cut its price. In other words, price responded to demand changes, but not to supply changes as there really weren't any. (it's more complicated than that, of course, but that'll have to suffice for illustrative purposes)
Enter satellite (full disclosure: I've made a bundle off of satellite. I'm gonna name my first boat the Echostar I). Well, now you've got more than one supplier. From a monopoly to a duopoly (OK, more than that, but not a ton of competitors), and not some cozy duopoly where they work out market shares in some back room. No, DirectTV and Echostar hated cable and wanted to hurt them. So while demand for TV continues to increase, prices moderate or even come down in some cases. Which is to say, prices are responsive to both supply (which increased by a large amount) and demand (which increases along pretty much its same plodding path). Better outcome, but less "responsive to pure demand."