Years ago, when I was in SPG's pilot Ambassador program (which I was invited to participate in before the program was launched), I got call from my ambassador asking if I was in Seattle because she noticed that I had checked into the Sheraton there. She thought it was weird because I hadn't mentioned it and I didn't book it through her. Long story short, it turned out that somebody had checked in fraudulently using my membership number. Fortunately, my credit card wasn't charged, but they did get upgraded because of my status. I don't know what happened to the people involved, but I was issued a new SPG number because of it. Based on the OP's video and my own experience, I guess people using other people's membership numbers is a thing.