I work with a mac mini and the external super drive. The importer window does not show the drive. Older posts recommend to use an internal drive, but of course ALL mac mini ONLY have external drives.
When I transfer the data to hard disk it is also not possible to import it. Other software does open the .vro file without problem.
I work on OSX Mavericks but I don't work with a Mac mini, so I've no idea what its special needs are.
But you should have no problem navigating to a properly configured drive, even if it's external. I frequently use an external drive as my media source for my iMac.
So I'm not sure what's up at your end.