The Chromecast is the tiny dongle that just keeps on giving. A mere couple of days after announcing support for a number of new applications, Google has let it be known that its $35 streamer is now compatible with Play Movies and Music on the desktop in a more native way. What this means is you will no longer have to rely on casting a Chrome tab to watch videos or listen to tunes ; instead, a Cast icon shows up within the Google Play web player and allows content to seamlessly be pushed to the device
http://www.engadget.com/2013/12/12/google-play-movies-music-chromecast-optimized/