Omega Share от Hermanos

▎ omega share turns any video page into a watch party. Open the popup on a page with an embedded video (YouTube, Vimeo, Twitch and more), pick a room, and click Share. The video loads in the room on the omega share website, where everyone's avatars sit together and watch it in sync, with chat.

▎ How it works: when you open the popup, the extension looks at the current tab only, finds its video embeds, and sends the one you choose to the room you choose. Nothing runs in the background and nothing is read until you click.

▎ Self-hosting: you can point the extension at your own omega-share server in the options page. It asks permission for that one server only.

▎ Open source (AGPL-3.0).