Look at the picture. The billboard is reflecting just a part of some bigger desktop. It can be that some real user who used that desktop got careless, moving so

Look at the picture. The billboard is reflecting just a part of some bigger desktop. It can be that some real user who used that desktop got careless, moving some opened notepad file with the login details to that area. Even if it wasn't too long, enough for that "hacker" to make a photo with his phone. Then the "hacker" later logged in himself, and also, being presented with the full desktop (over the VNC, probably?) but not seeing that part of what he does is also continuously reflected on the billboard, but seeing that he has full internet access (or maybe just the access to the local mp4?) carelessly clicks and watches. There's Chrome bar on the billboard, again just a part of the desktop. And he watches more. And doesn't get it at all what he's doing all that time: according to some reports, it lasted 20 minutes(!) until the power was cut to the billboard. Of course, a lot of photos with the phones again.