OMG. that is awesome.

I'm bit skeptic about this
it looks sometimes in slo-mo and at the end it looked reversed "really reversed not by the effect"
its playing with my brain can someone proofs this is a fake or not

It looks quite different in real life. This effect is caused by camera capture algorithms.

#3 No its not. Alot of people that have watched this video on youtube and stuff miss the whole thing about this effect, they think that the soundwave itself is producing the sick-zack water effect. If you look at the closeup though, the loudspeaker is just moving the hose in a sick-zack pattern.

You kan make the exact same thing with your hand and create cool pattern, just move the hose in circles, sick-zack or a pattern of 8 and it will look like this too......

This seems nice for the Wife when shes making dinner

#2 it is not reversed. you can see the water spread on the stones. It is the vibration making an optical illusion.

Hello, God? we've found another bug.

I've seen a similar clip on Snotr where the water from a hose was like frozen in mid-air by some lo-freq sound. Can't find it tho. Here's another one: http://www.petapixel.com/2012/10/24/commercial-features-water-drops-frozen-with-sound-and-the-cameras-frame-rate/

#8 http://www.snotr.com/video/9176

The sin-wave played by the speaker will change the way the water flows out of the pipe. Since the camera capture the film at 24fps, if you play a 24Hz sound-wave, you get a static effect because the water flowing out of the pipe is synchronized with the framerate. Play a 23Hz sound-wave, and at each frame captured, the water will be a bit late, therefore it seems to flow backward.

Filming the weels of a moving car produces quite the same effect.

#3 it does look different in real life, but that's because our eyes and brain process information at a different frequency (about 10Hz) and are quite adept at introducing their own illusions like motion blur.

If you took a photo of the water using a fast shutter, it would look like a sine wave, because that's what wiggling a hose would do. You'd get the same effect, but visible to your naked eye, by holding the hose in your hand and wobbling it back and forth.

The 23 Hz and 25 Hz frequencies produce a slightly different wobble which is not in the same place when the 24 Hz camera photographs each frame. Because of this, the wave form being produced by the audio and water appears to "move".

Interestingly enough, if you play a 48 Hz wave you'll still get a static display but with the wave peaks being much closer together. If you play a 36 Hz wave, (in theory) you'll get something halfway between, but with the flickering effect of two waves criss-crossing.

i say fake.
Call mythbusters!!!

I'm thirsty now

How about them apples? Wow, just wow. By far one of the best experiments I've ever seen.

The hertz is equivalent to cycles per second
1 hertz is hose moving back and forth .
So this hose does this 23 times in 1 second wich makes the water patern into sin waves

#3 = correct
#4 = incorrect

Actually, both #3 and #4 are right. The shape of the pattern is caused by the hose vibrating and the visual effect itself is caused by the framerate being (close to, or a multiple of, or a fraction of) the framerate of the recorded video.