It sounded like his solution was the idea of the sampled-down rss-esque feed, with the only purchasing taking place through the artist's own paypal-or-whatever

It sounded like his solution was the idea of the sampled-down rss-esque feed, with the only purchasing taking place through the artist's own paypal-or-whatever basket. The feed protocol needs to have some sort of cryptographic audit trail so that users can always reach the artist's sales page, and the artist can inspect, if necessary, where and how the distribution is flowing.