Showing the content of an area in another part of the stage

Somehow it seems to be possible to have 2 areas showing the exactly same thing, whatever that is.

In this Flash-based game:
http://www.towerdefence.net/games-100-Flash_Element_2.php

There is a spot marked “FETV”, this FETV changes to the surrounding graphics of an enemy or tower when such is selected.
How has this been implemented?