Lofaw pretty much nailed it.
And what's an antenna? Seriously though, people still have/use those? Nor do I want to play bounty hunter and track down feed after feed or site after site when the NFL or whoever shuts down the site I was using to watch games a week ago. Lastly, watching youtube videos online is one thing. Watching a 3, 3 1/2 hour game of football or a 2 hour movie on a computer is another. I've only watched one movie on a computer and it was kinda funky doing so. At least it was in full high definition. I've never seen or watched a sporting event/game online that was in high definition. That's not to say they don't come in high definition I've just never seen one in high definition.