well, it's still worth noting that one of the key elements in the demonstration is the ability to create a controlled sound frequency in order to get a specific movement. It's not just the fact that the hose moves... You could make the hose move any number of ways without getting these results.

An experiment, by definition, is the setting up of a test to see if a repeatable phenomenon can verify the existence of a postulated law. You already know enough about the laws that govern frequency, so you aren't inclined to assume the position of someone who needs to see evidence that proves the nature of waves and measurable frequencies.

Most of the fundamental laws of science were identified by experiments much like this

https://www.dropbox.com/sh/ey71h8ep047758h/AAC12jNM0Hz9Q8zsh5iDeqNHa?dl=0