I saw this before when the guy was fixing my TV. He was programming the channels I could see with a special remote and that remote went through every channel, including several porn ones. I thought they were subscribed to some porn channel, but I guess it makes more sense that someone was watching it and hence I saw 'their' channel for a second. I didn't say anything and obviously the guy hoped I didn't see nothing.

So somehow your remote had the proper setting to access the special menu. I'll leave the ethical questions aside but it was interesting to see how the system works