>Stream movies and TV shows while on a FaceTime call with friends. With synced playback and controls, you’ll see everyone laugh, jump, and react to the same moments at the same time. And the volume automatically adjusts, so you can keep talking while you watch.
> While sharing media during a FaceTime call, each participant views the content within your app running on their device
> if people must log in, download content, or make a payment before they can participate, display views that help them perform these tasks before showing the activity UI
> providing a free trial or special offer lets people sample your content during a group activity
As you can see, it requires everyone to own the content, and it also requires the other apps (like the netflix, youtube, HBO, or whatever app) to opt in to supporting it. I don't see any way this could be illegal.
It works with several streaming providers. The API is opt in though (Coordinated Media Playback), so the providers need to implement some hooks to make it work, meaning they've decided they have the rights.
Notably, Netflix doesn't allow it, but Disney+, Huly and HBO Max do.
Pretty sure this is illegal.