Every year, the sign above Discount's flashing marquee--Your Neighborhood Video Store Since 1981--represents a more impressive claim. Betamax has come and gone; Wayne Huizenga and his Blockbuster chain have boomed and busted; Title Wave has gone Hollywood; and Discount is still here in Minneapolis. This modest showroom is home to some 12,500 titles (search the catalog at www.videovendors.com)--enough so you can circle the more obscure selections in your Leonard Maltin guide with more confidence than prayers. Discount has the previously unreleased Cassavetes classics, the early films of Atom Egoyan, the mind-bending epics of Tarkovsky, and the documentaries that Blockbuster files under "Special Interest." And not to put too fine a point on it, your money won't be going to build a gator moat around the Huizenga estate in Fort Lauderdale, either.