How does it work? I will get right into it.
A thin sapphire wafer is coated with a micro-thin ceramic layer of yttrium barium oxide (which is a superconductor at low temperatures). Exploiting the Meissner effect, where a magnetic field repels a superconductor while it is transitioning to the superconducting state, the frozen disc will levitate over a set of permanent magnets. Due to the thin superconducting layer, the magnetic force passes through the material, at "weak points" in the layers follow paths called "flux tubes." Like with electric currents, the magnetic currents pass easily inside. With the magnetic field permeating the solid on all sides, the material will resist any changes. Hence, the "locked in place" effect.
Tel Aviv University physicist Boaz Almog explained the material further at the demonstration, "We have achieved what was thought to be impossible up until today: growing high quality superconducting layers on sapphire wafers. Since the superconductor is of the highest quality, it allows a micron thick layer to be locked in space with enough power."
The demonstration was held at the Association of Science-Technology Centers (ASTC) Annual Conference in Baltimore, Mayland, USA.
Unfortunately, this concept will not be seen in any new, futuristic, hovering applications unless the temperatures can be kept at liquid nitrogen levels. That is at 63 K (−210 °C; −346 °F) for those who are wondering. I am surprised the demonstrator kept touching the disk.
Eavesdropper