Why did they meltdown over that?

Sometimes our teens (...and all of us) have really big reactions to what appears to be quite small things that previously wouldn't have been a big deal but now end in yelling and screaming and punching a sibling. You're left worried that your teen has a massive problem with emotions. Thinking that they're going 0 to 1000 over the smallest thing, leaving you concerned they may have suddenly developed a major mental health problem or lost the capacity to self regulate. The video above helps to explain what might be going on.