Media Share

I have an external usb HDD hooked up to my wireless router and set up the folders for media share within the routers settings. When i try to watch movies, i get a message “there is no media available for playback”, but when i go to the music folder it finds those files ok and plays them. What am i doing wrong. I don’t want to network share as i want to be able to stream the media without having the PC on and taking up space on my PC HDD

Plug the USB HDD into the WDTV Live, it then becomes viewable across your network so you can move files on or off it via your Desktop, Laptop, Tablet using Explorer/My Computer.

OK tried that but it doesn’t show up in explorer. How do i make that happen?