Those that are hidden support those that are shown, but cannot be installed independently. They're installed automatically together with one of the shown modules, depending on what the plugin author defined in the update center.
If you have the full IDE installation, i.e., including the SOA pack, you also have Print and Print Preview functionality for the viewer:
Go here to get this plugin which, of course, could be used by any application that is based on the NetBeans Platform.
Update. I incremented the module version to 1.5 and removed the dependencies that were causing problems, with the result that you can now get the window, but not the Print and Print Preview anymore. Still, better than nothing.