H5P's may now be exported. For a long time we've supported importing H5Ps, now we've gone full circle and also supports exporting H5P's. This means that if you as an editor finds H5P content on another site, and that site has H5P export enabled, you may download the content, upload it to your CMS, customize it and share it.
Take a look at demo.h5p.org. Here the export feature is enabled and you may export content from here and import it to your own site, make customizations and publish it.