Tell the kids
http://www.dutchreach.org/ (reverse hands for UK)
Tell the kids not to ride in the door-zone.
The Dutch reach simply
doesn't work!
If you own a car try it. If you reach over for the door handle what you get is a good view of the door pillar. To see approaching cyclists behind and close to the side of the car you really need to use the mirror - and that should be adjusted to give the best view from the normal driving position. Even if you press your face aganst the window you simply cannot see the space door-zone cyclist will be approaching from
You can see this in the video (at about 1:07). First we see the driver turn and you can see him staring at the door pillar. Then we see the driver's eye view - initially a view of the door pillar plus a view straight out sideways. Then magically the cyclist comes into view at 1:08 - but only because the camera has been pushed out through the open window. Look at where the driver holds the door to shut it!
Indeed the fact that the video maker had to open the window (which of course nobody does when leaving a car) in order to make the technique appear to work shows that the video is fundamentally dishonest.