SIGNS (DVD, $8) AVAILABILITY Here’s a sign of security lapses: M. Night Shyamalan’s alien opus showed up in Manhattan’s Chinatown 11 days before release. PACKAGING A fuzzy copy of the movie poster. CONSUMER REPORT Is that shadowy figure behind Mel Gibson an alien, or just Joaquin Phoenix? On this blurry, umpteenth-generation dub of an audience taping, it’s impossible to tell. Cowards, take heart: Thanks to the distorted sound and indecipherable mise-en-scene, Signs’ big scares become laughable. You can’t see dead people…or anything else.