Plug it into your tv, select it as an input. Fire up the gootube app on your phone, hit the cast symbol on the app, then press play on a video, hit play again, and it will appear on the tv via the chrome cast. No need to be limited to watching those GCN videos on a tiny screen.
Also useful, when you're flicking through your photos and want to show one to others, tap the cast symbol in photos. And it will appear on the tv.
You can also cast from the netflix, prime video, bbc sounds, amazon music, and many other android apps. It basically makes a dumb tv semi smart.
J