The video was posted 2 weeks ago, but 3 weeks ago I still had to do the check-in on UX and SV on their respective apps even though it was ticketed and marketed by SV.

Also got an email from UX about the check-in ("now possible to check in for your flight to MAD") while it very much wasn't possible on the UX website until SV checkin also opened up.

I'll see what happens next week for the return flight, same itinerary but in reverse