This overlay is displayed by Method CSGO team members when they are queued for a game or match. It is designed with a great deal of open space to allow for the display of web cam feeds as well as Twitch Chat feeds or anything else that the streamer wants to display during the downtime between games.
The second image is the version of the overlay that is shown during a game. The area at the mid-top left is where the camera feed appears.
Note: Screenshots used are taken from Counter Strike:Global Offensive copyright Valve Corporation