When you choose the new menu item, the filesystem explorer opens and you can explore the contents of the selected package or folder:
It's quite handy. By the way, on the module's homepage it says: "By now all Win32 platforms and Linux with GNOME or KDE are automatically supported."
But the really cool part is that the module author has now also created an Update Center, specifically for this module:
(Go here to see the announcement of the new Update Center and instructions on how to use it.)
So, if you have modules out there that you'd like to publish, why not do the same? Follow the instructions in "Publish Plug-ins Painlessly! (Part 1)" to understand everything you need. If you click the link above, the one pointing to the new Update Center, you'll have a very nice example of a simple Update Center (mine is a bit more confusing because multiple NBMs are registered in my autoupdate descriptor, so the above autoupdate descriptor is much better as an example, because it contains the minimal things an autoupdate descriptor should have).
And, of course, don't forget to try out the Explore From Here module!
Update: See Part 3 for another Update Center...