During Microsoft's big Windows 10 event in late January, we learned that the company would be trying to tightly integrate its Xbox platform with the OS. That'll come to us in the form of an "Xbox" app, which will allow gamers to track their gaming achievements, chat to friends, view recorded gameplay, as well as receive a broadcast from an Xbox One so that games can be played from the PC.
In a May Xbox One update, the first hint of that latter functionality is going to become availabel. While more than just that feature will likely be added or enhanced, the streaming capability could prove to be the most notable.
Once live, a "Allow game streaming to other devices (beta)" option will be seen in the system preferences menu on the Xbox, and on the PC, an option to connect to the console will become available.
And, that's all we know at this point. Based on the screenshot, it doesn't seem likely that people will be able to configure streaming settings right from the get-go, although it could be that that will be controlled via the PC and not the source.
Currently, the Xbox app available in the latest Windows 10 build is unlikely to have this functionality built-in, but we're likely to see another preview build before this feature goes live, taking care of that.