TV networks and producers were initially cool to the idea of cooperating with social-television apps, the developers said. “A lot of them own a bunch of Internet sites of their own, and they aren’t wild that you might be pulling in stuff from somebody else’s site,” said Doerksen. “I get real resistance to Wikipedia from some people. It’s crazy because everybody knows Wikipedia is out there and everybody uses it, but we have to move slowly with a lot of these people.”

Farris said many television executives she approached are initially nervous that her Get*This app will undercut their commercials. “The last thing they want to do is compete with an ad that’s on the second screen,” she said.

But some networks have embraced the concept and set up their own shops to devise social-television apps. Kristin Frank, general manager of digital video at MTV and VH1, said her network uses apps to “eventize” its shows, turning each one into a major occasion. During the last Video Music Awards telecast, an MTV website featured an app called Hot Seat, a seating chart of the auditorium where the show was staged. A user could slide his computer mouse across the chart to see what celebrity was sitting there, along with all that celebrity’s tweets during the event.

Television, Frank said, has nothing to fear from social television. “All the platforms are a [transmission] pipe,” she said. “They’re the telephone, and we’re the conversation.”

If anybody in the interlinked universes of television and streaming video had any doubts about the overwhelming power of Internet social media, they ended on a Saturday afternoon last October when, during a concert in Los Angeles, the singer Usher broke the laws of fashion physics with a dance move that completely split the front of his pants.

Within minutes, fed by “Oh my God!” messages on Twitter and Facebook, the live video stream on Yahoo! had swollen from 1 million to 20 million.