If your car has the original 4:3 Video Module this should work (it worked on my 1998 model):

Watch TV / Videotext during driving

This works on all 5/7 Series with the Mark I Navigation System (the one with the male voice).

On Mark II (the newer version with the female voice) you have to use "brightness" instead of contrast for TV and "colour" instead of brightness for videotext to get the trick to work.

This works on the latest 99 7-series models as well. This does not appear to work for the latest BMWs sold in Europe (2000 onward, 3/5/7 series). The software updates for latest navigation CD-ROM's do not appear to affect or disable this trick.

1. set ignition to pos. II
2. enter TV mode
3. enter "settings"
4. enter "contrast" (BRIGHTNESS)
5. when the green contrast bar is visible, push the knob and keep it pressed
6. turn ignition off (keep button pressed!)
7. wait 8-10 seconds (timing must be accurate!)
8. release the knob
9. turn on ignition again

Now the TV will operate while the car is in motion, though you certainly should leave that to your passengers only while driving. To watch videotext use the same procedure as above, but choose "brightness" instead of "contrast"