Google has opened a beta program for the Google Cast Receiver app for Android TV as a means of enhancing the experience for developers, which in turn will seek to improve the experience for Android TV users who are using their Android TV to stream content to it just like they would a Chromecast. As Android TV has Chromecast technology built into it it's possible to fling your favorite TV shows and movies to any Android TV device that's hooked up to your television so long as the Google Cast Receiver app is installed on the unit, but there have apparently been complaints from users that the app isn't always offering a stable experience. The opening of this beta program hopes to change that.
As with all beta programs for Android, whether for Android mobile devices or for Android TV devices, you'll need to first become a tester before you can download the app to your device. Once you're a tester, you can download the app as only after this point will it show up for you in the Play Store. Since this is an app for Android TV, you won't be able to install it on a mobile device, but that doesn't mean you actually have to initiate the install on Android TV. If one is tied to your account you can become a tester from any device that's connected to the web with the proper link, head to the Play Store, and select the Android TV device that you wan't to install the app on.
Although this is meant to help users too, Google wants developers to be sure that their apps will work with the Google Cast Receiver, and as such highly recommends that developers enter the beta program as well so they can check to make sure that everything is working smoothly. According to a post from Google employee Nazmul Idris who announced the beta program for Google Cast Receiver on Google+, the aim is to check that apps are working a few days before they get rolled out to the public. Naturally, users and developers will need to be using the same Google account for the beta program as the account that's tied to their Android TV device, and since this is a beta there may be bugs which both users and developers should be prepared to experience in the event that any show up. If you're interested in becoming a tester, you can do so by hitting the button below which will take you to the signup page.