Designed for the fourth and fifth-generation Apple TV models, the new tvOS 12.2 developer beta can be downloaded onto the Apple TV via a profile that's installed using Xcode. Once the initial beta has been downloaded, subsequent betas can be installed over the air.
tvOS 12.2, paired with iOS 12.2, lets users ask Siri to play specific media on an Apple TV from an iOS device. You can, for example, ask Siri to play Modern Family on the TV in the living room. This works for music and TV content.
No other new features were discovered in the tvOS 12.2 beta as of yet, and it can be difficult to determine what's new because Apple does not provide release notes for tvOS betas or releases. If additional features are discovered in tvOS 12.2, we'll update this post.