All right then I'm definitely going to have a glossary in the full game to help non-bandos out. Thank you for giving me this feedback. I'll try and define some of those terms while you're here...
Drum Major: The conductor of the band.
The Pit: The front ensemble, which consists of instruments that can't be marched with such as a xylophone, gong, etc.
Low Brass: A family of brass instruments that play in a deeper range including baritones, tubas, and trombones.
Color Guard: The flag twirlers.
Dressing: Looking down the line or curve and making sure you're in line with everyone else or conforming to the shape.
Mellophone: Since French horns aren't a marching instrument, mellophones are the substitute. They look like giant trumpets, but sound like French horns--it is the instrument Poptart is holding.
Mezzo piano: A measure of volume. It's relatively soft--Peter is mocking Clark in that his instrument can't play nearly as loud as his own.
I hope that helps! And Squall looks like a very good boy.