I'm not very smart, I'll admit that but I think it has to do with the the way the camera is recording the water? It is being vibrated in such a way that it is only recording certain frames. In other words, the water doesn't look like it's in suspended animation if you were seeing it live.
He's recording at 24 fps, so yes you're correct. The FPS at which he's recording isn't so relevant as long as the Hz he's using to create the effect is the same (for freezing animation), 1 above (for forward), or 1 less (for reverse)
It's an optical illusion generated by the camera. The hose is actually bouncing, but the camera isn't recording at a high enough FPS to capture it all as it would really look like in person.