Yeah "water purity" is a grey zone, lots of scams. When I was young I earned some cash as a handyman. The stuff some people wanted me to install in their water system was baffling. Especially since I live in an european country with probably the best tap water quality in the world.

edit: just watched the vid, hillarious, they are just disolving the toxic metal particles in the water holy moly and use distilled non conductive water for the "proof". Yay humanity!

I think he means electrolysis. Putting a current in a solution (e.g between two metal prongs) makes the negative and positive charged particles flock to their according charge. Or new particles form. Its how the metal industry applies small films of materials to objects.