Please please please can people stop overusing "emo" now. The word is more overused than the look and that is getting out of hand on its own. It even says in the video it's not emo. They have dark outfits and dark hair. So do I, and I am not emo.
/mini rant.
And while this is fairly old news, I agree with the mother. If this is the worst thing they're going to get up to in school then good for them, it's probably better than going out every night getting paralytic, having unprotected sex with as many women as possible, failing lessons due to hangovers and getting into huge fights. Sure, it doesn't coincide with my view of convention in society, but it's a lot better than underage drinking and street fights.