Valve is now jumping into the pool of livestreaming. With the launch of Steam Broadcasting Beta the service will allow to watch friends play a game, while still being in the client. While also being able to stream right from your client. The plan of this is to greatly simplify streaming for everyone. You can also select who will be able to watch your stream.
There are also limits to the system, like browser support. Also you can’t invite people who aren’t currently are your friends list. And maybe the worst, is your livestreams aren’t being archived.