Here's another video of a little contraption of a similar design that is demonstrating the same feat in a difference frame of reference: rather than travelling faster than the wind over a static ground, it travels against the motion of a treadmill in static air:
Now, whether or not these videos are fake, is such a thing possible? We're not talking about breaking conservation of energy or momentum: there's lots and lots of moving air, so we only need to decelerate some of it to speed up our hypothetical cart. It seems unintuitive, but it's not immediately clear that it should be impossible. Pulleys and levers can seem unintuitive the first time you encounter them.
I'm actually inclined to say it's possible. Am I wrong?