Water trick using sound waves and recording frequency

This is a very nice trick, where the water appears to be frozen in the air, sometimes moving up and sometimes moving down. This is due to the recording frequency, which is 24 frames per second, getting the same picture of  the waterfall constantly, giving the illusion of a frozen wave. At 25 hz, the water appears to fall at one frame per second, while it goes up at 23 hz. Amazing!