A monster attacks New York. Written by Drew Goddard and directed by Matt Reeves, the new twist on the old plot is the brainchild of producer J.J. Abrams (Lost): a monster flick as “found video,” shot from the viewpoint of the faceless extras who, in other such movies, get crunched and munched while the stars are making their escape. Goddard and Reeves give it the virtues of a good monster movie (suspense, cool effects, nifty mayhem, characters we care about—but not too much), and, alas, the flaws of bad home video (wildly shaky camera work, sloppy framing, jagged editing, often poor lighting). It’s an interesting Blair Witch-type experiment, but the verisimilitude of the amateur-video style was enough to send at least one viewer out with a raging headache. The cast of unknowns performs with conviction.