The title should say "high Tc superconductors" (Tc is the transition temperature, which used to be really really low decades ago) and not high-temperature superconductors as the latter could easily imply higher-than-room-temperature to those not familiar with the subject...
For more information on these experiments by Eremets & Drozdov:
Silly question: WHY do superconductors enable hovering trains ?
Because in order to drive the electro magnets you need a large amount of current. This causes a large amount of heat waste due to resistance which is essentially lost energy. If you have superconductors there is no waste heat making MagLev trains much more efficient.