I've loved this song for a long time, had never seen the video for it until this morning. While I'm no longer a disaffected youth, I still say "scream your heart out!" Why the fuck not? Whether you have something you want to get off your chest, or whether you're so happy, you want to let the world know, just shout it out!
Try not to think badly of all the emo children in the video (I include the band!), I was once emo, too. Before they even called it that! Ask me about my emo poetry sometime. It made my kids laugh! ;)