I tried to add this as a comment, but it is too long so I am
making this an answer instead. This is not my text, but the text
of one of the commentators on the video: "Superconductors are of
two types, which are defined by their Meissner effect. One type
repels magnetic fields, which will levitate the superconducting
object. A type I superconductor becomes a perfect diamagnetic
material, which exhibits a magnetization in the opposite
direction of an applied magnetic field. The Meissner effect
creates a complete diamagnetic material so that no magnetic
field lines are present in that material. I doubt this will
suspend the object against gravity by putting it on bottom, for
the magnetic fields in opposition will impose a force on the
superconductor in the same direction as gravity. There is what
might be called an anti-Meissner effect where the
superconducting material collimates magnetic flux lines into
narrow tubes or vortex fluxes. If the magnetic field at large is
not perfectly uniform it takes work to mov