An eye-grabbing headline at Slash Film yesterday screamed “Cloverfield National Sneak Preview Screening Next Tuesday.” But reading the item you discover these Jan. 15 screenings of what will either be the first big hit of the year or another “Snakes on a Plane” are not open to the ticket-buying public. You have to win or pick up a ticket from a sponsoring newspaper, store or radio station. We call those promotional screenings, kids.