It's fairly simple to get the beta on your own Apple TV, though we don't recommend it. We're still sore from last September when the latest iOS 10 beta bricked our iPhone. Still, if you're super curious and don't care if your Apple TV stops working, you can sign into the Apple Beta Software Program with your Apple ID on your Apple TV, enable the Public Beta Updates option, then let the box download and install the latest beta tvOS. If you want to send feedback to Apple, you'll also need the iOS 11 public beta for your iPhone. But seriously, don't do it unless you're willing to brick the thing.