I took the black plastic EZ-Start controller apart and mounted it inside the car with the battery pack that powers it.
Then I wired a microswitch to the connection points of the RED button on the EZ-Start controller.
Next I mounted the microswitch close enough to the end of the brake rod so that when the Throttle trim on the transmitter is in center position the switch is not activated during braking.
But when the Throttle trim is all the way to the left the Brake rod activates the Microswitch during braking.
Watch the video again. If that doesn't help I will make a more in depth video for you.

So the way it looks from the transmitter.
To start the car you turn the Throttle trim all the way left.
Then you apply full brake (activating the switch and the EZ-Start controller).
Then the cars starts. Next you turn the Throttle trim back to center.
Then you give it the throttle and drive away.

Thanks for the interest.
PepsiKid