When sand is in an atmosphere it contains air that is compressed as the a/not's feet exert force upon it as he jumps up.
As the feet move away from the surface an area of low-pressure is created under the feet, and surrounding air rushes in to fill it, including the compressed air within the sand. This rush of compressed air upwards takes with it numerous sand grains and so we see a sand cloud rise directly beneath the a/not's feet. Young is jumping in an atmosphere and so is not on the Moon!