Google now launched the Support for YouTube Live streams. Earlier Chromecast can only cast the videos from the YouTube. Google initially enabled casting of YouTube live events from the desktop back in April, however this new announcement allows casting from mobile. Announced on the Google Chrome Google+ page.
Google Chrome  Google Plus Page :-
“With Chromecast available in 18 countries and YouTube live streams happening on the regular, we wanted to share one of our favorite ways to use Chromecast. Head to one of the live streams in the YouTube app, just press the cast button, then kick back and enjoy these live events from the comfort of your living room”
In Germany live stream will not be available because the German law (RStV), you must have a broadcast licence from the media authorities when you make a live stream that can reach more than 500 people at the same time