I can't blame you if you blew up. I mean, you tried to reprimand them softly at first, but they still didn't listen. And the fact that you prepared a lot for it and believe me a 5-minute speech is NOT easy. Though the time seems short, it requires lots of paragraphs just to finish it. Saying things is different from writing things. You may have written 5 paragraphs but if you say it, it only takes 2-3 minutes. That is very inconsiderate of them. Although, I'm wondering, how did the other people react to their actions? Did they helped hushing them, too, or stayed silent?