>>> the broadcast you're watching tonight is on an over-the-air television network that is supposed to arrive at your home for free if you have an antenna to bring in the signal. two big over-the-air networks are making the initial threats they'd rather come off the air and go on cable alone instead if a new technology is allowed to go through that would take their signal and charge you for it sending it directly to your device through the internet. our report on all of this tonight from nbc's john yang .  >> reporter: it wasn't that long ago that families would gather around the television to watch big events. shared national experiences.  >> they've got the flag up now. you can see the stars and stripes .  >> not guilty of the crime of murder.  >> reporter: now viewing has gone from this to this. nielsen researchers say more than 5 million american homes don't have a tv set but that doesn't mean they don't watch tv shows . 67% of them get content on some other device.  >> reporter: a new service called aerial is the latest delivery system capturing tv programs as they go out over the air and bringing them to your device by way of the internet.  >> there is no consumer equipment to buy, no boxes, cables. you can simply go online, sign up, and you have a great experience on any device that you would like.  >> reporter: currently only available in the new york area the company plans to expand to 22 other cities this year. it's cheaper than cable. but unlike cable companies , aereo doesn't pay net works for the content they spend hundreds of millions of dollars to produce. aereo says the service is legal because each user has their own antenna just like one in a home or an apartment. one per user.  >> aereo thinks it has found a legal way to distribute live television over the internet from the broadcasters without paying them.  >> the president of newscorp which owns fox calls it piracy and vows to continue the fight in the courts. nbc universal filed suit as well. if aereo ultimately wins fox and univision say they might convert to pay cable channels forcing all consumers to pay to view. it would be a sea change in how we get and watch television. already, cable, dvrs, and streaming video have given viewers more control.  >> there is must see tv that you decide you will watch when you want to see it. and i think that's the fundamental change.  >> reporter: in an industry where change seems to be constant.  >>> john yang , nbc news, chicago.
Video on msnbc.com: Some broadcasters are considering moving their product exclusively to cable now because of a new way of distributing TV programs online.  NBC’s John Yang reports.