Most of the expensive explainer videos out there have this element: a guy typing on his laptop. You can modify the color and it’s best to include in videos where such graphics are needed.
You can also slide it into your video or duplicate it when you need multiple desks. To make the final video better you should change the colors if you chose to have multiple desks in the same frame.
The audio file can be bought from here: http://audiojungle.net/item/successful-journey/1037525