https://thenextweb.com/basics/2020/09/04/how-to-use-twitch-new-watch-party-feature/

Amazon is really beefing up Twitch’s capacity for non-gaming content. The latest feature it’s added is “Watch Parties,” essentially a way for streamers to host themselves watching Amazon Prime content, with their chat watching along. Here’s how it works.

Watch Parties are now available worldwide to any creator with a Prime or Prime Video subscription. Kick back and enjoy your favorite movie or TV shows together on Twitch.