Follow up on terms of NARA-Amazon agreement

More on the publicly-funded, public-domain films in the US National Archives and Records Administration (NARA). Under its deal with CustomFlix, the private corporation which digitized the films, NARA can post OA copies to its web site only if (1) NARA buys digital copies from CustomFlix and (2) CustomFlix has already amortized its costs through sales of TA copies.