Magnetism is a force like gravity and so can act against (or indeed with it).
Even a static magnetic (or electric) field can levitate suitable (metallic) objects and therefore reduce the effects of gravity,
You're referring to accelerating a magnetic field by rotating superconducting magnets 6,500+ rot./sec. which do lose weight and eventually lift off the faster they spin. The most similar macro events outside the laboratory would be electrogravidynamic tornadoes, as well as the gravitomagnetic process of solar flares.
The carrier particle of magnetism is a photon. As far as a magnet is concerned a photon is
The faster the magnet rotates, the closer the magnet comes to
The preceding is an incredibly dumbed down version of this. If somebody understands this better, please rewrite the above.
Now consider the experiment outside the lab where the magnetic iron content of the sun compresses at various gravities and temperatures within itself and rotates against it. The heavy iron apparently compresses as a sunspot near the much lighter hydrogen surface and explodes out anti-gravitationally as a flare that quickly reverses direction, and thereby polarity, and falls right back in.
This is not really anti-gravity but equal poles opposing each other.
Always remember that
I might always be wrong.