This video contains a SERIOUS error at 41 seconds. The video gives a measurement of 225mm each side of the centre line for drilling the holes in the wall. The dimensions should actually be 275mm (i.e a total width of 550mm). If you follow the video instructions you will end up with holes in the wrong position, but too close to the correct position to enable you to drill another hole securely. Guess how I found out...?!