How to watch the videos you took by Nikon d3100 using a computer?

How do you watch the videos you took by Nikon d3100 using a computer?

Copy the video files form the camera to the computer.
Double click the media file you just copied.

Since you did not tell us which computer or operating system, we don't know uif you need to load a media player that can deal with the MOV files the D3100 captures.

When in doubt, download and install VLC Player from www.videoLAN.org - this assumes your computer is using some flavor of Windows or Macintosh OSX.

As for copying the video files - we presume you already read the manual on connecting the camera to the computer with a USB cable and getting the camera into computer mode. Or you cave a flash memory card reader attached/in to the computer and can copy the files over…

You download them to the computer as per page 115 of your manual. Then you use the video program that came with your computer or the one that came with your camera or one you choose to buy.

Upload them.

Put the memory card in your computer, a window will pop up asking what you want to do. Import it.
Jim is right, upload, not download.