It was on the jumbotron - surely one or two of the thousands of people at the show knew who it was. And then we'd have people watching it remotely, or the show appearing on video services, etc.
Assuming this was discovered via "Social Media Surveillance" is a leap, and a weak argument about such surveillance (which is a real problem that I've been arguing against since the late 90's).
Again, this was on the jumbotron. Stuff on the jumbotron has made the media circles since the advent of the jumbotron.