By default  Windows Media Player 12 (WMP12) adds files automatically from various locations of computer to the library during playback. This results after playing a video, you resume or replay the previous playlist.Right click Windows Media Player button on the Taskbar and there you’ll see “Resume Previous List” option in the WMP12 Jump List. When the latest opened media file playback ends,you will get “Play Previous List” option.







If you like to stop this you can follow these steps:-

1.Open Windows Media Player.

2.Click Tools and then Options.

3.Under the Options click Player tab.

4.Scroll down to player settings and remove the  check marks in these two boxes :-

   a] Add media files to library when played and
   b] Add remote media files to library when played



5. Click Apply/OK.