In the video, Bungie details on their motivation behind bringing Clans and Guided Games to Destiny 2.
According to the devs, they heard fans cries for an easier method to fill groups to play end game activities. To make this happen, Clans and Guided Games are coming to Destiny 2. Clans, much like Guilds in MMOs, will offer clan based progression for hitting weekly goals, as well as offer a means for solo-players to jump into Guided Games.
Guided Games are essentially the in-game Looking for Group for both clans and solo players to get a big enough team to participate in activities.
Destiny 2 is set to release on September 8th, 2017.