I’m a geek. How does this really work?

ZvCast software uses MPEG2 compression and Dolby Digital processing to turn the video and audio of your computer into an actual digital cable HDTV channel in real time. That channel is “localcast” over the home’s coaxial cable wiring, and can be tuned in by any HDTV with a digital-cable compatible tuner, also known as a QAM tuner (they’re quite common).