OMG I actually laughed out loud a couple times watching this video! Its like, I could see the color change when the note was a little out of tune AND the quality of the line got a little bumpy if the tone was a little scratchy. I think something like this is more fun than anything else. I would be so distracted by the novelty of how the visuals changed that I wouldn’t seriously expect to learn anything from the kind of feedback it provides. Anything that provides a visual feedback to pitch does not train the ear to hear the correct pitch on its own, and then associate that with the muscle memory of placing the finger in the right spot.