JWPlayer is an in-browser multimedia player made by Longtail Video. Islandora uses it to create players for objects using the Audio Solution Pack and Video Solution Pack, so that they can be streamed directly inside a user's browser instead of requiring them to download it to their own computers first.
The JWPlayer library is free for non-commercial use, but only version 6.12 of that library is compatible with the Islandora JWPlayer module. Unfortunately, the website jwplayer.com no longer allows new users to register as legal users of version 6.12. The only free version they offer now is version 7.x. This is not a problem for current users of JWPlayer version 6.12. They should feel free to continue using it. Otherwise, for new implementations of video on Islandora we highly recommend using the video.js library instead. You can get information on the Islandora Video.js module from the Release Notes and Downloads page.
Check the Audio Solution Pack and Video Solution Pack pages' configuration sections for more information on how set JWPlayer as a viewer.
This module has been updated to use jwplayer6.