The first trailer deals with Nicaea, the in-game website where deaths are predicted in video format. Not only do the protagonists see themselves show up on the site, so do the deaths of others - making the site a useful tool to help you save these people.
The second has a look at some of the gameplay.
Devil Survivor 2 releases in Japan on July 28th. If you plan on playing Devil Survivor Overclocked first (or if you're like me, and you're still on Day 4 of the first Devil Survivor...), the second game is due out next year in North America, and Overclocked sometime this fall.