BBC Doctor Who Advent Calendar Day Three

Earlier today, the BBC's official website for Doctor Who made the third 'door' on their Advent calendar available to open. Today's surprise in the Advent Calendar is a video going behind the scenes of the recent Doctor Who special episode, The Waters of Mars, to find out how Gadget, the robot of Bowie Base One, works. The video can be seen inside the third 'door' at the official Doctor Who website by clicking here, and the fourth 'door' on the Doctor Who Advent calendar will be available to see from tomorrow. What are your thoughts on this behind the scenes video?