Libraries on the "desktop" not available in metro

I believe this is a win8 problem, even though I'm running it in a virtualbox I dont think that is the cause, it only showed me the problem. (maybe I'll post this in the VM forum too)
As stated, I got win8 running in virtualbox. It installed no problem. Took a little effort to get my virtual win8 to see the "real" hard drive on my win7 machine (had to RTFM and install "guest editions"). So now my virtual win8 can see my local drives. So far so good. The problem then became that the local drives that win8 sees are actually seen as network shares. This meant I could not add them to libraries, hence photo apps, video apps etc see no media. With some more effort and lots of googling I managed to get the network shares added into the libraries. I thought all problems were solved, NOT!
Note that all this tweaking was done in the desktop mode...
Even though win8 sees libraries with tons of media, when I start one of the included metro apps for photo's or video's it still says there is no media!
So the desktop see's libraries with lots of stuff, metro see's nothing! "Metro" cant be looking at its own seperate libraries can it? that would be dumb. Does anyone know what might be going on here?

metro, as well as media center (same behaviour was in win7) is building it's own database (cache) of media files, located in configured libraries.
have no idea if it will support remote locations, maybe you'll be able to add them as another media source (in metro app settings) or research if it is possible to set it up as media extender.
you can try to set up lan connection between host and vm (many vm's support that option), and then turn on sharing of media for this network connection on your host computer.