Follow these steps:
1.Open VLC Media player.
2.Click on Media — Select Capture device.
3.Now you can see new window, select Desktop from Capture mode.
4.Now select framework from Options menu. Ex : 20 f/s.
5.Finally select Convert from drop down menu of play.
6.Once you click on convert, you will.get option of file format and destination. Select format and destination of your choice.
7.Finally click on Start and then press play button Now whatever activity you doon Desktop will automatically get recorded.
Once you are done with recording, just go back to VLC and stop recording.