Using a tube, a piece of tape, a speaker, and his camera, YouTuber MrBibio created an effect that makes water droplets appear to float in midair.

He explains the optical illusion in plain English:

[Y]ou're actually seeing 25 different drops every second, the uniformity of the waveform being played through the speaker is vibrating the pipe in a uniform way, so the drops exit the pipe uniformly, the frame rate of the camera is synced with the speaker so the drops appear static, the short shutter speed means the drops appear sharp and frozen in mid air, a longer shutter speed would show motion blur.

In other words: Magic.

[reddit]