It's worth noting that most airlines can view most tickets given the name and ticket number (you can use the saudia website to view the gory details of tickets issued by most TAs and airlines yourself if you wish). Whether or not they do is a separate question, but United certainly do check (partly since the itinerary can grant lounge access even if the flight you are taking next doesn't).

Same with Delta. Whenever I check in they pull more information than what's on the ticket. I would be amazed if they don't do simple validation to see that the PNR/name/etc... match their systems.

When I have a physical ticket, and change my seat on the app, they usually re-print my boarding pass with the new seat number on it.

This might work for some non-airline run partner lounges without flight data access, but usually those have "coupons" given by the check in agent for access. The video shows someone entering a Star Alliance lounge, using self serve scanners. They probably aren't network connected like a normal check in agent stand