Structured as a nonprofit, the start-up aims to succeed where Aereo was litigated into oblivion. On the roof of a luxury building at the edge of Central Park, 585 feet above the concrete, a lawyer named David Goodfriend has attached a modest four-foot antenna that is a threat to the entire TV-industrial complex. The device is there to soak up TV signals coursing through the air — content from NBC, ABC, Fox, PBS and CBS, including megahits like “This Is Us” and this Sunday’s broadcast of Super Bowl LIII. Once plucked from the ether, the content is piped through the...