Mirko Paoloni and Andreas Mangold went down a nice street to film some boarding!
Some longboarders are starting to use radios as a form of communication on the road, where someone either on the ground or in a car will radio to a boarder and warn them of upcoming hazards like cars. It's a good idea for safer longboarding on open roads, in theory at least.
Mirko took a radio with him and got all the information from the car a couple hundred feet in front of them. However, a radio is no good if you don't warn everyone else in your crew with a hand signal. Andreas didn't have a radio so he couldn't hear any of the alarms.
Even when Mirko did warn Andreas, he usually did it so late that it was obvious there was a car. Just remember, if you are going to take safety precautions actually use them, doing it half-assed is just like not doing it at all.