Host a public watch party

Set Who can join to Everyone and your party is as public as a party gets here: people already watching the same video can see it is on and join, and anyone with the link can walk in, with an account or without one. There is still no site-wide directory of parties to browse.

A party is public when its Who can join choice says so. The row sits right under the Start a watch party button and starts at Invite only, so a public party is a choice you make: Everyone is the open door, and it is the one setting that shows the party to people already watching the same video. Anyone who reaches it can join.

What still does not exist is a site-wide directory. Nobody can browse a list of live parties from the home page. An Everyone party is visible to the people on its video and to anyone holding its link, and that is the whole audience.

Open a party to whoever turns up

Open the video and open Watch Along.
Look under Start a watch party. The quiet row beneath it reads Who can join and then your current choice, which starts at Invite only. Click the row and pick Everyone. Its description says exactly what you are agreeing to: anyone can find this party and join.
Click Start a watch party.
Click Copy link for the vdr.fyi link, right in the People room, or open Show QR code, behind the gear on desktop, if you want a code people can scan off a screen. The QR dialog is titled Scan to join and repeats the link underneath as text you can select.
Post the link where your audience is. People on the same video can find the party without it, but the link is the only route in for everyone else.
Expect people without accounts. Someone who opens the link signed out gets two buttons, Sign in and join and Join without signing in, and the second one works. You do not need everyone to sign up first.

What people arriving actually see

They land on a poster page, not the video: WATCH PARTY, then Watching together, then your masked name and started a watch party, then a count of how many people are here now. One press of Join puts them on the video with you, following your play, pause and seek.

What to keep in mind with an open party

You cannot take one person out. Ending the party ends it for everyone; there is no per-person removal.
Party chat is live and disappears when the party ends. It is not kept.
You are masked by default, and so is everyone who joins, so an open party does not put anybody's account on display.
Watch Along never appears on videos marked as made for kids, so those videos cannot host a party at all.
The link keeps working as you move on. If you go to another video, the party goes with you and the same link still resolves. See Watch a playlist together.

If you wanted a listed, browsable party

The closest thing is Everyone plus a well-placed link. An Everyone party is found by the people already on its video, but there is no browse page of live parties and no way to opt into one. Post your link somewhere your audience already reads, and start the party a few minutes before you want people in it.

What's next

Host a private watch party covers the other four choices, and why the Visible, Masked and Hidden control is a separate thing entirely.
Watch Along covers the rest of the panel.

Host a private watch party

Set Who can join before you start. Invite only takes the party off the public surface and lets in anyone holding the link. Followers, Friends and A group go further: they check every arrival at the door, so even someone with the link is turned away unless they belong. Everyone is the open party, and Invite only is what a fresh picker starts on.

Invite a friend to a watch party

Open the video, click Watch Along, and click Start a watch party. The panel shows a QR code, a short vdr.fyi link, and a Copy link button. Send your friend that link and they land on a join screen, signed in or not, and press play with you.

Watch Along

See who else is watching, press play together in a watch party, and chat while you watch.