Looks like Steam is coming into the Steaming game with Steam Broadcasting. You can watch your friends stream any steam game talk to him through a chat system that your friend can see.
How it works?
When you see a friend in game, Select “Watch Game” from their profile or from the friend’s list to open a window into their gameplay.
Wanna try it now? Here is how!
Both you and a friend need to opt into the steam client beta, in the steam client main menu. Select settings > Account and change your “Beta Participation” to “steam beta update”
Who can watch the stream?
You can decide who watches your stream, The first time a friend asks to watch your game you’ll be presented with the broadcast privacy settings
How do I start & stop my broadcast?
When you’re playing a game and someone starts watching, you automatically start broadcasting. When you end the game your broadcast ends.