mojo, I thought you had it working? I tried all sorts at first and I couldn't get it to work. I was doing it wrong, and I tried everything except the right way. This works everytime for me,
1)Play a DVD
and get it to the correct volume.
(if you alter the volume it will bring up the settings page and you will have to stop the car again and repeat)
2)Start the car moving and then when the screen goes black.
3)Pull up at the side of the road. (The DVD will start to play again)
4)Press the "i" button (just for a milli-second) and Mrs Sat-Nav will start to say something.
5)Immediately press the "TONE" button. (this will make a beep)
6)Set off again with the DVD playing
.....p.s...If you do access another display page other than the DVD, it will reset. So then you have to go back to number 3).
Also, I think it is very handy to have this feature as is. I'm not sure if its legal to have a DVD playing whilst driving, but should someone notice, (rozzers) you can quickly adjust the volume and it will reset. Then if you need to prove that it won't play when moving... just set off and it will show the black screen.