One of the videos shows Xbox Live programming head Larry "Major Nelson" Hryb and Richard Irving from the Xbox engineering team going over the new Home screen for the update. It will allow users to scroll down to see their most recently used games and apps on the Xbox One Pinned items are placed at the bottom of the Home screen, and there's a tips box on the side of the most recently used apps that offers information about recent update for the Xbox One.
The second video takes a look at the Guide, which first appeared on the Xbox 360, but has been revamped for the Xbox One. Scrolling left on the Home screen will bring up the guide, with the first view being an Xbox One owner's friends list. The Guide's user interface also allows users to start or manage a party of players, with text chat for up to 12 party members. The Guide shows messages between offline members, notifications and more.
Source: Xbox (YouTube)