The company is testing the feature worldwide in Facebook Groups during certain sports events, including UEFA Champions League matches. It'll eventually spread to "all kinds of live events and cultural moments," Facebook said, citing award shows and premieres as likely candidates.
Facebook isn't just catering to TV junkies today -- it's also courting music fans. If you attach a song to your profile, you can give visitors an option to listen to the full song on Spotify (see below). More music partners will be available in the "near future," according to Facebook, so you might not be out of luck if you or your friends prefer other services.
It may seem unusual for Facebook to enable Watch Party for videos that aren't even online, but this appears to be more about capturing your attention than making money. If you stay in a Facebook space while you're watching the big game, you might be more likely to stay on the service for after-match discussions.