How can I drag and drop files to Nexus 7 from a Windows PC? I have a Nexus 7 tablet and Windows 7 computer. I can see the tablet in the device manager as a Nexus 7. It shows up as nexus 7 when I view it on my PC as a drive.

When I drag a photo to the tablet from the pc, the photo file on the nexus 7 shows up there. I cannot view the photo no matter what I do on the tablet, it says 0 photos. I also cannot get any video file to play on the tablet after I drag and drop it.  No sign of it on the tablet, but I can see it in the folder on my pc. 

I am using USB. This is so frustrating.
Please see that the photo and video formats are supported by default. Else you might need to install apps that are available in google play. Use a file manager to open the picture by browsing to the location. Once you open it, they might start appearing in the gallery automatically.