Can't stop the rock
Very much in the spirit of Spellbound (a brilliant documentary about serious kids who take Spelling Bee competition to hardcore levels), you don't need to know anything about Harry Potter or even like the franchise to appreciate the DIY enthusiasm it inspires among large groups of people. There's nothing cooler than kids grabbing guitars and forming bands inspired by books, then rocking out the library!
At the very least you should check out the trailer:
There's another screening for the film in NYC this Tuesday, March 8th at the Anthology Film Archives.