All public libraries pay $2 per play for each film. A film is triggered immediately once a patron clicks 'play' and the film loads successfully. The patron then has 3 days to watch before another $2 charge is incurred for the same film.
Please keep in mind that most public libraries have a plays limit per patron. (e.g. Los Angeles Public Library only allows their patrons to play 10 films per month.)
(Related Article: How Do Public Library Views Count Towards Royalty Reports?)