How in the World does This Happen?

[cnowels]

Okay, a friend of mine recently got a nice new HDTV so I was helping him get setup with the over-the-air HD channels we have in the area. (Really nice strong signals here.) Particularly, if I keep my regular coax cable connected to the TV. Oddly enough, I don't watch any SD cable channels, but if I disconnect the coax - then my HD reception degrades. I assume that it is actually using the coax running through my house as an antenna - so I'm cool with that.

What has me confused is that my friend gets one additional HD channel that I do not. Interestingly, this channel is somehow what someone else (in his neighborhood, I assume) is watching. Sometimes, it will be HBO, Cinemax, or even Porn. You can actually watch this person flipping through the channels on this one single digital channel. AND - the show even pauses at times! (while the user goes to the bathroom or something, I guess)

I am perplexed as to an explanation! Could someone actually be broadcasting whatever they're watching on a digital channel so that some other TV in their house would pick it up?