I've never really cared much for the whole Buffy phenomenon, myself, and I didn't care to attend any of those screenings, but I know plenty of people who had fun with it, and it's sad to see one of the nicer theater gimmicks in recent memory go the way of the C&D -- especially when it really did amazingly well in the Coolidge midnight shows. I've heard the showings routinely sold out and when the Coolidge's main auditorium sells out, that's sure some box office boffo.
If Fox had any sense, it'd take a cue from the sing-along versions of MGM's Wizard of Oz sing-alongs or even The Sound of Music -- hell, that's a Fox property already!! -- and officially license the screenings, but industry execs and their pet sharks in Legal aren't always the paragon of common sense. Granted, an episode of a television show isn't on par, universal brand recognition-wise, with the Wizard of Oz, but in the right markets (and Clinton totally knew this) the Buffy sing-along event would rake in the money hand over fist.
So it goes.