NEW YORK (The Street) -- Is Netflix (NFLX - Get Report)  about to lose a lot of content?

In comments made in London to a television industry gathering this week, Discovery Communications (DISCA - Get Report) CEO David Zaslav expressed frustration that Netflix is gaining subscribers on the popularity of television shows and movies produced by media companies whose stock prices have largely fallen this year.

"Where's Netflix without our great content?," Zaslav said in comments reported by The Telegraph. "How many iPhones would you buy if all of our stuff wasn't on there?"

Put another way, when does aiding the growth of streaming services like Netflix, Amazon (AMZN - Get Report) Prime and very soon, an expanded AppleTV (AAPL - Get Report) , accelerate the decline in pay-TV subscribers? Pay-TV, after all, provides the largest source of revenue for companies like Discovery, whose shares have plummeted 29% over the past 12 months.

Though the question of whether Netflix is more friend than foe isn't a new one, its gained increased attention over the past year as the decline in pay-TV subscribers has accelerated. The pay-TV industry in the second quarter lost 566,000 subscriptions, according to a study by MoffettNathanson. Nielsen estimates that over the past year, the number of cord-cutters has totaled 1.2 million households out of roughly 100 million.

This week, the cries over Netflix appeared to get louder.

James Murdoch, CEO of 21st Century Fox (FOXA) made clear in an interview at a Goldman Sachs investment conference this week that his company's relationship with Netflix, and other video subscription services, is "evolving." In June, Fox signed a licensing deal with Hulu that includes its hit show Empire after negotiations with Netflix fell through.

"We have a long partnership with Netflix that has been good for both sides," he said on Wednesday. "But we increasingly do more and more business with Hulu."

Murdoch said Fox sees advantages to sending Hulu more of its content, in part because it shared ownership of the platform with Disney (DIS - Get Report) and Comcast's (CMCSA - Get Report) NBCUniversal but also because Fox receives payment on a "per subscriber basis," and as Murdoch told the Goldman conference, "it's a business where we control much of the ad inventory, we can control ad loads and we can really innovative in partnership more."

Netflix declined to comment on its relationships with content producers.

By contrast, Fox's contracts with Netflix have been "fixed fee deals" which didn't allow Fox to determine when to make available previous shows in an episodic serial. As for future deals with Netflix, Murdoch said he's more likely to "approach it differently."

Time Warner (TWX) CEO Jeff Bewkes was another media executive who expressed concern that Netflix's growth has accelerated "cord-cutting," the industry term for pay-TV customers to terminate their contract. Content companies, whether they're Time Warner's Turner Broadcasting or an independent producer, must reconsider under what conditions streaming platforms such as Netflix take control of a particular show or its full season, he said.

"The real question is, what is the offering that the premiere exhibition network should have for a given show," Bewkes said. "And what is the window, and when is it that the subscription video-on-demand aggregator ought to have it."

In other words, can media companies regain more control over their content. That appears to have been the reason that Epix chose to move its content to Hulu from Netflix, removing such hits such as The Hunger Games: Catching Fire and Transformers: Edge of Extinction, as well as older classics such as the original Rocky and its sequels, from the streaming platform's catalog. Epix, which is jointly owned by Viacom's (VIAB - Get Report)  Paramount, Lions Gate Entertainment (LGF)  and MGM will move its content to Hulu on Oct. 1.

Whether the loss of content will curb Netflix's meteoric growth remains to be seem. Subscriptions ballooned to 65.6 million worldwide at the end of June with 43 million coming from the U.S. as Netflix has mostly aggregated content from television and film companies around the world.

Just how significantly the growth of streaming services is cutting into pay-TV remains another source of debate.

Despite a steep decline in Viacom's stock price, CEO Philippe Dauman told the Goldman Sachs conference that "cord-cutting" is being overblown, and that streaming platforms offer new opportunities for distribution rather than cannibalizing its traditional revenue stream.

"People are totally overplaying this," said Dauman, whose stock price has tumbled 40% this year. "When we're looking at it, there's not a material deterioration. In certain segments were actually seeing stabilization in the cable-TV universe. And as new players come in, you're going to see that the overall universe is a healthy one and that distributors are doing their part to create value."