It was a cryptic tweet from BBC America, but one that certainly had the twitterati a-flutter:  “@Twitter (News - Alert) and @BBCAmerica, home of #DoctorWho & #TopGear, ink deal to offer 1st in-Tweet branded video synced to entertainment TV series.”

And that was it: no further details and no explanation. No media exclusives and no press releases. But there is, however, precedent: ESPN (News - Alert) and Ford had a similar arrangement with Twitter to provide ancillary content for live college football games last season. ESPN pushed out companion clips, sponsored by Ford Fusion, that were watchable within Twitter itself rather than requiring the viewer to click out to a Website--making for a new revenue stream for media company and social media doyenne alike. It also worked with Turner Broadcasting earlier this year in a near-identical arrangement to tweet instant replay clips from March Madness games, sponsored by AT&T and Coke Zero. That partnership was enabled by SnappyTV, which provided underlying technology to deliver 15-second video highlights.

“The instant replay applies classic Twitter strengths, mainly mobile and real time, to video,” Glenn Brown, director of promoted content and partnerships at Twitter, told the New York Times. “You get an alert on your phone, you can run into a bar and catch the rest of the game,” he said.

When it comes to @BBCAmerica, it is likely that the two are experimenting with second-screen concepts. Video clips and other content can be pushed out, synchronized to the on-air experience, offering behind-the-scenes content or exclusive extras, all, of course, of interest to marketers looking for highly engaged TV viewers.

The move is a savvy one—Twitter has gone through several monetization ideas over the years, from “premium accounts” to promotable tweet services, to brand-able feeds. Advertising to its 288 million active users is slowly starting to pay off for the microblogging service though.  eMarketer (News - Alert) estimates that its worldwide ad revenue is projected to be $545.2 million in 2013. By 2014, Twitter will account for 13 percent of U.S. social-advertising ($807.5 million), compared with 5.5 percent last year ($288.3 million). 

According to the forecast, more than half of Twitter's ad revenues—about 53 percent—will come from mobile advertising this year, up from virtually no ad revenue from mobile in 2011. By 2015, Twitter is expected to reach $1.33 billion in worldwide ad revenue, more than 60 percent of which will come from mobile advertising, eMarketer said.

That’s still a fraction of the $205 billion marketers spend on TV around the world, but the key thing to consider is the level of engagement on offer. A recent report from Nielsen and SocialGuide showed a strong correlation between viewer engagement and Twitter commentary.

“We expected to see a correlation between Twitter and TV ratings, but this study quantifies the strength of that relationship,” said Andrew Somosi, CEO of SocialGuide. “We see three key factors. While prior year rating accounts for the lion’s share of the variability in TV ratings, Twitter’s presence as a top three influencer tells us that Tweeting about live TV is likely a significant indicator of program engagement.”

Don’t expect the model to do anything else but grow. Bloomberg reported that Twitter is talking with Viacom (News - Alert) and NBC about similar partnerships that would let Twitter stream videos from their sites, while splitting the ad revenue with the networks. “One or more deals could be reached by mid-May, and Twitter may strike deals with other networks,” Bloomberg (News - Alert) noted.