Amazon says it may sell ads for those slots, but says it will also use them to promote the company's other video offerings.

The rest of the deal is roughly similar to the one Twitter had last year: CBS and NBC will each broadcast five games, and Amazon will stream the networks' coverage, including their ads. Amazon will have the rights to sell a handful of ads slots per game.

Amazon is paying around $50 million for the 10 games it will show next fall, according to a person familiar with the deal. That's a big increase from the $10 million Twitter paid for last year's games .

This year, pro football will continue the test, but will switch it up: Amazon has bought the rights to the league's streaming package, and will offer the games for free to its Amazon Prime subscribers around the world.

Kam Chancellor of the Seattle Seahawks forces Calvin Johnson of the Detroit Lions to fumble near the goal line during their game at CenturyLink Field on Oct. 5, 2015, in Seattle.

Amazon won't have exclusive streaming rights for the games. CBS and NBC will also have the ability to stream the games they broadcast, and Verizon will stream the games to its wireless subscribers.

The deal is Amazon's first significant foray into live streaming (besides Twitch, the live video game streaming platform it bought a few years ago), and its first major move into sports; Amazon has also worked with the NFL on "All or Nothing", a behind-the-scenes documentary series that debuted last summer.

But Amazon has been ramping up its interest in live sports. "For us, this is about starting to bring live sports to our Prime members all around the world," said Jeff Blackburn, the company's head of business development and entertainment.

Last year, when Twitter beat out Amazon for the NFL games, both Twitter and the NFL made a big deal about the fact that Twitter had around 300 million users worldwide. And they said Twitter could reach even more people with NFL games, because it wouldn't require anyone to log in to Twitter to watch them.

This year, the NFL seems to have made a different calculation. By putting it behind its Amazon Prime paywall, Amazon will reach a smaller potential audience. Amazon has never disclosed its Prime subscriber numbers, but my colleague Jason Del Rey thinks the company has 66 million subscribers; some Wall Street analysts think the number is higher.

But Brian Rolapp, the NFL executive in charge of the league's media deals, argues that Amazon should be able to find at least as many viewers as Twitter did, since Amazon Prime members visit and use Amazon a lot.

"Reach is a focus of ours. I think Amazon has been able to demonstrate, in everything that they do, massive scale," he said. "I don't think this is limiting the reach. I think this expanding the reach."

It's unclear what benefit streaming the games actually provides for a digital platform. Last year both Twitter and the NFL said they were pleased with the results of the experiment, but the games didn't generate a huge audience: They averaged less than 300,000 viewers per minute, while CBS and NBC averaged 15.8 million viewers.

—By Peter Kafka, Re/code.net.

CNBC's parent NBCUniversal is an investor in Recode's parent Vox, and the companies have a content-sharing arrangement.