I think this is from around September 5th.
Jade Raymond, lead developer for Assassins Creed, talks about how their main goal for the game is to create a new and redesigned gameplay experience. They have two main ideas they are focusing on, the first being a huge free roaming world, and the second being unique crowds that react to you based on your actions.
They also go around the studio and talk to different members of the Assassins Creed developer team, which is very interesting.
Watch the video below: