Don't take no chances with people like this. Lock the windows and drive away. If they follow you, call the police and drive into the nearest garage, blasting the horn. What's the betting they were filming the car so they could use forged plates on another, stolen vehicle? Not that? So what other reason would they have to film? It might be lawful and it might be a public place, but their actions appear to suggest their motive is far from innocent.. if they're reading this? Come here and provide an explanation!
This is why people are resorting to on-board cameras, whether they're in a car, on a push-bike or lorry etc... driving like this is becoming more common.
Bus lane driving white van man, dangerous driver, uses van to drive at you to intimidate. Violent and aggressive bully.