It doesn't have to be onboard. this is for any videos.
The reason for the removal of the in-car camera is a safety one. Regardless of how silly it may seem, having been deeply involved in world motorsport safety issues, I can tell you that a camcorder mounted on a sticky mount can quite easily kill you in an accident. The marshalls are doing their job.. keeping the balance between safety and fun. Don't give them a hard time mate.