This is absolutely not what happens in this video:
And if this is still not satisfactory - how about a treadmill of infinite length? Then we can see if the vehicle slows down and speeds back up. As shown in this video, your prediction is, again, absolutely not what happens:
And here the University of Berlin shows the same setup:
The cool part is these are all experiments you can do. Set it up and let it run for 5 minutes or whatever. Other people have, contrary to your lies, done these experiments and shown that stored kinetic energy has nothing to do with the propulsion of the vehicle beyond the wind speed.
I'm not even that interested in this problem and I found these demos and evidence of Cavallaro's research in 2 minutes of Googling. Yet you sit there and claim neither he, nor anyone else, has tested these things to rule out your ad hoc explanation (that no one in the entire world, except you, subscribes to).
That is why you are lying.
What you see in that treadmill video is a treadmill powered fan.
As long as vehicle body is constrained to ground in any way it is nothing else than a treadmill powered fan. The charged energy can not be used so it is charged and remains charged.
The circular setup is not equivalent and has nothing to do with the linear treadmill experiment that is a good equivalent of the faster than wind direct downwind version as long as the body is not constrained in any way as in both of those videos you linked.
It is not just me that understands how this vehicle's work and there are people that have a way deeper understanding than I do since this is not my area of expertise apart of energy and energy storage where I'm by definition an expert.
Thus the claim (indirect) of breaking the energy conservation that got my interest. I did learned quite a bit more while trying to explain how it works and also learned more what is that many people have problems with.
I narrowed down to Newton's 3'rd law and energy conservation.
The explanation Rick and his believers including Derek of how the direct down wind vehicle works is this.
Get energy from the wheel (not understanding that energy comes from vehicle kinetic energy) then use that energy to power the propeller.
This is the entire explanation and sound exactly like you get a generator connect that to a motor with some gear ratio may be and you have a perpetuum mobile in fact even overunity.
The only way wind (moving air particles) can power any vehicle is by colliding elastically with the vehicle body and so transferring kinetic energy.
When vehicle is above wind speed it can no longer be powered directly by wind power as no particles will be able to collide with the back of the vehicle as vehicle moves faster than the air particles in exactly the same direction.
But the part that is ignored is that air is a compressible fluid so air particles still hit the back of the vehicle because when vehicle was below wind speed it used wind energy not only to accelerate the vehicle but most of it it was diverted to propeller that created a pressure differential thus storing energy allowing vehicle to exceed wind speed for a limited amount of time proportional with the amount of stored energy.
I can build a vehicle without a propeller that can exceed wind speed directly downwind using another form of energy storage like say a supercapacitor.
All you need is a small ideally foldable sail spend some time below wind speed to charge the supercapacitor then use that energy to exceed wind speed.
It will be cheaper less dangerous than the 20m^2 swept area propeller and achieve the exact same thing witch is to say fairly useless thus the reason you do not see any commercial applications using this.
But I need to insist that we return to the question with 4 possible answers as that will provide the missing understanding and it will be a good point to start and understand why this wind powered vehicles are not what they appear to be and do not work as advertised.