The first one is a nitro engine, which looks like it could be actually controlled. I would think the guide wire would be their to help maintain it going it a circle. I would think the throttle would be the radio controlled part of that vehicle.
The second video is an R/C car.
You got to remember that technically Radio controlled means anything that can be operated via a radio transmitter. So really that first car could have just radio controlled brakes.
The only way to really know is to go to an event like that or research more about it I guess.
Just throwing in my .02