You can already enter text on your Apple TV via Siri, a Bluetooth keyboard or a connected iOS device. Adding a similar feature to Twitter, already a text-centric platform makes a lot of sense, though the implementation is a pretty complicated. Once you update Twitter on Apple TV and find a video to watch, you'll have to swipe left on the Apple TV Remote. Once you do, you'll see an option to connect to an iOS device running Twitter with a long press on the Remote touchpad. You'll need to confirm the connection on your iPhone or iPad running Twitter, then the Apple TV app will give you the option to "Send this Tweet to your device." You can then tweet your reply via your connected iOS gadget and the Twitter app.
The option only seems to work with Live Twitter broadcasts, and the various swipe and click gestures take a few minutes to really "get." Still, the ability to comment on live videos you're currently watching could help engage more folks than before.