The other possibility is they took a small sampling set deliberately from a section of population thats statistically more likely to be pirates, high school pupils for example. And then upscaled the results to form a "statistic" (I place it in quotation marks because any "statistician" doing that deserves to be beaten to death.......... with probability distribution tables). I don't know if they've done this, haven't seen an indepth breakdown of the analysis and the data that generated it.
Although, to be honest it looks like another attempt by the industry to prop up a lame business model, and a stubborn refusal to kill the business model. Seriously, whats the problem with trying to create Streaming services, like many UK channels have done. Has no-one in Australia/USA worked out that if you give the people a legitimate way to watch the programs/listen to the music, that it stands a good chance that they will? Or that you can do whats know in broadcasting as "advertisements" to raise funds to do such a system/make money?