I use a Nikon D7000 to take movies.?

Looks like your computer is up to the task.

The program you're using is not. Windows media players of any sort are substandard and should never be used unless you want to frustrate your enemies.

Media Player Classic (better known as MPC-HC) is my favorite player as it has good scrubbing controls (allows you to use the slider control to move about in the video).

VLC is another excellent video player and has more features than MPC.

Both these media players are free.

You can indeed use most DSLRs to shoot movie, and I have used a D7000 to do so,, and transferred its output to my computer. But much better is to use a proper camcorder.

Try playing the video on your TV. If the video works okay, the problem is your computer's video codec. You need to update it. If it's jerky on the TV, try shooting with a new and faster memory card.

What we don't know:

Your computer model and operating system (and version).

Configuration of the computer (need RAM and available hard drive space).

Location of the video file when you try to play it on your computer.

Media player being used for playback.

Frame rate is only one of many items that can contribute to the smooth playback. So is the amount of compression used by the camera on the captured video.

Where are the videos when you play them on your PC? If they're still on the card the transfer rate may be too slow for smooth playback.