I saw this video on levitating a denser liquid on less dense air by vertical shaking. But I couldn't understand some points in the video.

1 : How did the liquid levitate at 0:37 or at any one of those moments?

I think it's because of vibrating the air in the vertical direction, which causes it to apply a force on the liquid in the upward direction.

Is there any mathematical model of this force so that we can find the exact frequency for this levitation?