I think computer-controlled hologram is not here yet.

I heard the news report that the avatar is a hologram or laser projected. I figured this is wrong, it's a rear projection (http://en.wikipedia.org/wiki/Rear_projection_effect). Two digital projectors (huge boxes one above the other) beam from the back of the stage onto transparent screen. In some shots the upper edge of the screen is clearly visible, in other it's the whole screen.