There are just a handful of video services that support voice controls on the Google Home, like Netflix and Google Photos. This allows you to start playback of content on a Chromecast, Android TV, or other Cast-enabled device using Google Assistant voice commands. I'm still waiting for Hulu to add support, but in the meantime, you can now use it with YouTube TV.
The new functionality works just like every other service on Assistant. You can say things like "Play Disney XD on YouTube TV" or "Play The Orville on YouTube TV." You can also ask to record a show, play a specific movie or the latest episode of a TV show, turn captions on/off, and play/pause playback. The full list of commands is available here.
If you're not caught up with recent improvements to Assistant, you can also set a default TV in the Google Home settings to make the commands less tedious. So instead of saying "Play The Orville on YouTube TV on the living room TV," you can just say "Play The Orville on YouTube TV." Sometimes you can get away with leaving out the service ("on YouTube TV"), but occasionally Assistant will get confused.
- Google Blog