When those replacement NFL refs blew the call in the Packers vs Seahawks game on Monday Night Football, a single play generated more than a million tweets. A recent study from Yahoo and Nielsen showed up to 86 percent of viewers use a mobile device while watching TV. And so money is pouring into so called "second screen" apps that give users access to additional content and conversation around their favorite shows. Startups like GetGlue and Miso have raised big funding rounds, in GetGlue's case from industry titan Time Warner. Today a new player hits the U.S. market with some heavyweight backers, as U.K. based Zeebox launches stateside with investment and content partnerships from Comcast-NBCUniversal and HBO.

TV stars say, "what do you think?", and in real time the audience can respond

"There are a lot of players working on second screen apps, its a very fragmented space," said Page Thompson, the executive vice president of strategic integration at NBCUniversal. "We looked all around the world at the startups doing this, and just felt the technical team from Zeebox was the best." Since it's launch in late 2011, Zeebox has signed up 1.5 million users. "They've proven their product in the U.K. market, they've got that entreprenurial spirit," said Thompson. "They can move fast, but the product can scale."

Zeebox, like many other second screen apps, is a mix of social media and modern TV guide. If you log in with Facebook or Twitter, you can see what friends and followers are watching, which programs are trending, and what shows are recommended for you. Tap through to a show and you can grab all kinds of digital goodies: outtakes, interviews and biographical data on actors. Zeebox comes loaded with extras for 307 shows across the NBCUniversal network. It can display schedules and statistics for any show you like, but only some providers, NBC and HBO for example, are fully integrated with the app.

"We didn't want to just be another choice in the app store," said Anthony Rose, former CTO of the BBC's iPlayer and Zeebox's co-founder. "Second screen has been smart tech folk creating very cool apps around other people's content. That has been great because you can innovate, you can take risks, but to take it to the next level, you need deep integration with the companies that are producing the content. We want TV stars to look out at the audience and say, 'what do you think', and in real time our audience can respond."

Rose's comments are intriguing. As we have seen with Apple, playing nice with old media can be very lucrative. But if it means Zeebox takes fewer risks, and is less innovative, that's a drawback. It's especially true because Zeebox will be heavily promoted by NBC. "You're going to see ads for it across our channels and websites. There will also be live mentions on air, where we may ask the audience to vote for contestants or decide what bits a late night host will try the next day, and direct viewers to the Zeebox app," said NBC's Thompson. "We're all in." Hopefully Zeebox will succeed or fail based on the merits of its app, not its primetime promotion and celebrity calls to action.

"We didn't want to just be another choice in the app store."

Compared to the U.K., the United States presents a much more complex challenge, with an wide array of different regions and cable providers. Zeebox hopes to premier a feature in a few months which allows users to change the channel on their set top box using the app on their smartphone or tablet, a feature which already exists in the U.K. "There are more technical hurdles here, to be sure," said Rose.

Zeebox pulls down a wealth of data about live TV and uses audio analysis, closed captions, and video fingerprinting to generate interesting "z-tags" about the subject matter. The company also gives publishers a set of APIs and editorial tools to push graphics, video and web content back and forth between television and the app. "We think these two worlds are coming together, and this will help to erase the boundaries that remain," says Rose.

Of course the same principles apply to advertising. The $70 billion ad market in the U.S. is a very juicy target. "I don't want to lose site of the key consumer proposition, but the money that will fuel this change in the future is advertising." says Rose. "Can you marry web and TV advertising? Right now it's not interactive, its not targetable by household, not clickable."

Rose imagines a scenario where a character on your favorite show gets in a Camaro, and suddenly the car drives across your tablet, where you can rotate it 360 degrees, change the color of the paint, and compare prices for different models. And while a premium cable channels like HBO don't advertise to its subscribers, it can find a new revenue stream pushing ads against its critically acclaimed shows on the Zeebox app.

Cord-cutters who dumped cable and used their television to watch content from the web used to be a relative minority. But the latest report from NPD says TV sets are now the number one device for watching streaming video. With the proliferation of Smart TVs and devices like Apple TV and Microsoft's Xbox, the living room screen is becoming a hub for all entertainment, regardless of the source. "TV won't just beam out at me, it will be interactive, like the internet," says Rose. "We're ready to push things forward in a big way."