wow... damn good demonstration.

This is a false ad and this concept has been proven to be a gimmick. If you put a different light such as UV on your face, of course you see different things. That doesn't mean these things are bad or will cause surface appearance issues. And yes, if you put something on your face first, changing the conditions, (and blocking the light) you will of course have a different outcome. By their logic peanut butter, mayo, or hemorrhoid cream is also good for you. I'm not saying you shouldn't use uv protection when appropriate, but this is just bad science.

Even the last girl's teeth were turned ugly by the UV.

It states in the video that "glass blocks UV" - that's not accurate - different glasses have different transmission spectra, so it depends on the glass and it depends on the UV wavelength.