2011 may be light on horror films, but that's all about to change with the coming release of 'Paranormal Activity 3.' The third film in the nearly $400 million-grossing phenomenon arrives in theaters on Oct. 21, and -- judging from this new 30-second teaser -- you can expect the film to scare the pants off you and yours through Halloween and beyond. VHS tapes! Invisible demons! Creepy little girls! Watch ahead.