Judge Nathan admitted that because of her ruling, the broadcasters are going to suffer some harm when setting rates with advertisers. By taking viewers away from the traditional television set, it will appear that fewer viewers are watching a particular network and could result in lower ad rates being charged by the network. She also mentioned how Aereo had grown from 100 users to 3500 this year and said that some viewers had commented that the service might allow them to cancel their cable service.
The Judge said that she would have ruled in favor of the broadcasters if not for a prior ruling by the U.S. 2nd Circuit Court of Appeals in Manhattan in a case challenging Cablevision's Remote Storage DVR system. In the decision, which was made in favor of Cablevision, the latter was found not to have violated copyrights when it rented remote equipment that was comparable to what the users could have purchased for home use. Right now, the service is available only for New York City.
source: AP via TUAW