Two good places to start are http://en.wikipedia.org/wiki/Associated_Press and http://www.ap.org/pages/about/faq.html. As you mention, AP is a cooperative, owned by its members. Member organizations both contribute content to the AP (often by default), and get the right to re-print or re-broadcast its content.

As with most cooperatives, the AP is a separate (not-for-profit) corporation, with its own board of directors primarily comprising executives from its members, and its own CEO, Tom Curley. Given that, I would expect that the AP, as an organization, acts in its own self-interest. One could imagine that this includes defending its IP against re-use by those who are not paying for it.