Nicked from another forum......
Apparently this was a road safety film(!) being made on the Isle of Man.
The whole thing is a set-up that went wrong. The film maker is called Stuart Peters and accepts blame for the foul-up. The copper is real, but was 'acting' the role of a radar operator under direction.
Here's the whole thing:
Btw, bike 1 stops, bike 3 stops. It's only biker 2 that has the problems, even though he was expecting it. And there's no speed limit on that stretch of road.