The changes sweeping through the media business have not left C-SPAN untouched.

The service, probably best known for its coverage of Capitol Hill, has begun requiring viewers of some of its heretofore freely available online content to log into using the credentials given to them by their cable or satellite provider. "Once this policy is in place," the network says, "the live feeds of our three television channels," as in, C-SPAN, C-SPAN2, and C-SPAN3, "will be reserved for cable or satellite TV customers."

Why the switch? "Somebody has to pay the freight for this," says Peter Kiley, C-SPAN's vice president of affiliate relations. Indeed, C-SPAN seems to be confronting something its colleagues in the newspaper, magazine, and television businesses are also facing: its online popularity is, at least in the short term, imperiling what has been its core business model.

The move reveals two things that have long been true, but hidden. The first is that C-SPAN is a service of the cable and satellite industry -- its name, in fact, is an acronym drawn from "Cable-Satellite Public Affairs Network -- while the service draws on the work of government institutions for much of its fodder, and it's cable industry funds, not taxpayer dollars, that pay for the company's $60 million annual operating budget.

The second is that C-SPAN blends straightforward coverage of government events with original programming that it produces.

Understanding the nuances of the new "hybrid" model, as Kiley calls it, takes a bit of attention to detail. Live streams of congressional hearings and floor activity will still be available a la carte without a cable log-in, but the streaming quality will be somewhat lower than what is available to registered cable customers. Meanwhile, shows like "Washington Journal," "The Communicators," and Sunday night's "Q&A," hosted by founder Brian Lamb, will only be available live to those logging in through through accounts with Time Warner Cable, Optimum, Xfinity, or another cable provider. Still, all of C-SPAN's content will be freely accessible after the fact in C-SPAN's online video library.

The goal is to make the C-SPAN experience slightly better and more expansive for cable customers, to help continuing justifying that industry's expense on the service. Kiley says that the network looked at data showing we're quickly trending to a time when most TVs will capable of natively streaming online content. That seemed like a warning sign. "We get paid for putting pictures and audio on televisions," Kiley puts it simply. "If there's such an end run around through a device like an Apple TV or a Chromecast or just a smart television -- well, our business model didn't look very sustainable."

C-SPAN's always-on live stream is, Kiley points out, a bit of an anomaly in the TV business. "That was a nice thing to do while the Internet was getting going," he says, stressing that the network cherishes its role as a public service. "But as technology has developed, we had to consider whether it was the right plan for us. We're like everybody else in this industry: we looked at what happened with the Olympics, March Madness, the World Cup," that is, with so many people eager to consume those experiences online. "It's self-preservation, and it's looking towards the future."

While much of the online reaction to the change has been strongly negativeCarl Malamud, the long-time public advocate who has pushed to increase the public's access to C-SPAN content, says that has long as all of the network's "government stuff" remains available to stream live and watch through its archives, he's fine with the new plan. As he sees it, that content is "a gift to the Internet, and to me, we should just say 'thank you.'"

But what about those without cable, including so-called cord cutters, or those of us who have stopped watching television through traditional cable or satellite services altogether, and thus just don't have a log-in to punch into to watch a high-quality stream of a White House press conference in the Rose Garden or "Book TV" in real time? Kiley hesitates a bit. Then he says, "We're very proud of the service that we're able to provide. And we take pride in the fact that we do it as an independent journalistic organization, and we take pride in our distributors." In other words, expecting the cable industry to worry about non-cable customers getting the content it pays for might be asking too much.