An airplane will not take off on a treadmill if it is maintaining its position. I will relate this to someone running on a treadmill for comparison sake, since almost everyone has been on a treadmill. If you stand on a treadmill, it will move you backwards. You have to run/walk to at exact the same speed in the opposite direction to maintain your position. If you do this, your upper body is in a stationary position. You do not gain nor lose ground. Step off the treadmill while you are maintaining this speed and you instantly go forward. Stop running/walking and you instantly go backward. There is no airflow around you, since you are in a stationary position. Remember when you were young and stuck your hand out the window of a moving vehicle? You made a “wing shape” with your hand? If you tilted your hand up, it would lift your hand/arm. Opposite if you tilted your hand down. Try this next time you are on a treadmill, no airflow over or under your hand. Without airflow, a plane will not fly.

If you think because the propellor is turning, creating airflow to fly, then just look at the above video. Why would the plane need a truck then to pull it down the runway before it would take off from the platform? Think of the platform being a treadmill and the floats being the legs. It is maintaining its position on the platform, no forward nor backward movement. Even with the propellor turning, the plane still needed a certain speed forward before it reached a speed it could takeoff.