WD app on windows 8 PC does not show all movies

I installed Windows 8 the other day and tried WD app just about an hour ago.  I have a 3 TB  WD MyBook connected to USB that contains a couple hundred movies that I ripped from the DVD and Blue-Ray disks I own.  Of all those movies WD app only recognized two of them.  Each movie is stored in its own folder and I have downloaded cover art (some pjg and other ico) in the folders.  WD App displays the cover art as just pictures.  The movies are stored as *.mp4 

How can I make it see all the movies I have?

Which WD app? Which NAS drive?

I have no idea which WD app – it looks a lot like Microsoft Multimedia app on Windows 7.  All it says is WD on the screen.As for the drive, I already said it’s a 3 TB My Book drive.  I don’t have a problem with the hardware.