Law enforcement agencies around the country are experimenting with technologies developed for the wars in Iraq and Afghanistan. These high-tech video recording can track whatever moves in an American city for hours at a time. One of the, called "wide-area surveillance" is like Google Earth with a rewind button: a kind of time machine, allowing police to review a crime and also track what happened before and after. It and other new technologies, including facial recognition, might even lead to stopping crimes in progress. But they're way ahead of the law. Will they increase public safety at the price of eliminating privacy in public places?