The method used to catch would-be predators is derived from that normally used by Perverted Justice. Perverted Justice volunteers build a profile of a clearly underage person on social networking websites and enter chatrooms as decoys, waiting for predators to initiate a chat. Such chats, which are always logged, sometimes turn sexually graphic, and some result in appointments for sex.
For the Dateline NBC stories, would-be predators are invited to an undercover house used by Dateline NBC for the duration of the operation; in accordance with Perverted Justice policy, phone contact is always established with a suspected predator before any appointment is set up. The visitors are led to believe that the supposed minor is home alone, and upon coming inside the house, are soon confronted by Hansen, who interviews each one at length about their intentions. After this, Hansen identifies himself as a Dateline NBC correspondent and informs the visitor that the entire interview has been recorded on hidden camera as part of the Dateline NBC story. If law enforcement officials are involved in the operation, the predator is then promptly arrested upon leaving the house. The arrest is sometimes made in a dramatic fashion by multiple officers who, with guns drawn, ambush the suspect and command him to lie on the ground face-down before he is handcuffed. On occasion, a predator will attempt to avoid capture and arrest by fleeing. Tasers are sometimes shown being used to subdue fleeing[1] or unresponsive[2] suspects.
Chris Hansen, the presenter is really cool. He sounds like a 1950s gentleman when he starts grilling them. Here's some videos of it:
http://www.youtube.com/watch?v=wUGeIeRtnwk
http://www.youtube.com/watch?v=h5OZzp7HSKs&mode=related&search=
http://www.youtube.com/watch?v=IPUZYSZLrJA&NR=1
A few good parodies of it as well, like this one:
http://www.youtube.com/watch?v=hKUkwh8TmM0&mode=related&search=