Police cars - Video input

Heya folks!

I had a bit of a curiosity about this for a while.

On most of the Dutch & Belgian police vehicles that drive with VAG vehicles have a function where they can display video on the OEM infotainment that their onboard camera has recorded.
Most of these are just ordinary Amundsen of Columbus units that don't look any different than consumers get.
I'm curious how this is done?

wiring diagrams show no video inputs for these radio's, except for a simple reverse camera.
The police cars are able to display video when driving too.

Is this a separate emergency vehicle only module somewhere?