Here is what I have confirmed so far.
The camera in the van is made up of two components, the video component and the IR laser component.
The laser component sends pulses out every 1/3 of a second and uses these to record the change in distanceover this time. The video is slaved to the laser to get a recorded image of the vehicle that is being tested.
The laser cannot operate when the vehicle is moving as this introduces a form of doppler effect that would throw the reading out - so there is little chance the video was recording too.
Also, these vans are ususally one person opeations, so if it was being driven then there will have been no-one looking out the back.
Finally, from 'ofuckthat'sacameravan' experience of my own I saw one being set up, the camera oes not appear even to be in position while the van is in transit - but that may depend on the area and van setup.
Good luck, what I found seems positive for you