Upgrade of libraries
I guess this "howto" is still valid and that the downloadable file near the bottom of the page is updated in such a way that the upload of this file will lead to "updated libraries" (?!)
https://groups.drupal.org/node/444178
To find the "right place to upgrade libraries" on the Drupal admin panel:
Home -> Administration -> Content + the tab to the right: "H5P Libraries". Then it is just to upload the newest library file revision (?!)
(Please correct me if something is wrong.)