What? It's a DVR?
It gets is programming from Over the Air. The article doesn't make it clear that all you need is a [modern] TV to watch Over the Air digital broadcast TV. If you have an LCD TV, switch the menu to "Antenna," plug in the cable from an antenna, and watch the free TV, signals -- which has less compression than cable and satellite. At your convenience, play with some antennas -- which vary from cheap and simple to $100 and are intended to be installed on the roof -- and see what you can get for free. The bigger the antenna, the more signals you'll be able to receive, but if you have a city nearby, then a cheap, simple, even indoor antenna will get all the networks. When you need a break from experimentation, just switch back to your usual cable or satellite. Conversely, if you got plenty of signals coming in for free, then you won't be the first to cancel your cable or satellite after discovering all the free TV.
Check
http/antennaweb.org/Address for a good estimate of what signals will be available at your location, how strong you can expect them to be, and therefore how small or large an antenna you would need to receive each signal.
The article compares Plex to Sling, Playstation Vue, YouTube TV, Hulu, and DirecTV Now. But it doesn't compare Plex to running the antenna directly into your TV or getting a DVR for free digital broadcasts. That's where the article should have started.