AT&T customers who are also DirecTV subscribers can now watch streaming TV content without using their mobile data.

To do so, they'll need to download the latest version of the DirecTV or U-Verse apps. AT&T bought DirecTV last year, and quickly moved to integrate many of the two companies' offerings.

"Our customers want to take their TVs with them, and our new DirecTV app allows just that," AT&T exec David Christopher said in a statement. "You can get the content you want, when you want it.... your living room channels and your recorded content with you, anywhere you go."

As is typically the case with data-cap exemptions, there are some caveats. While just about all of the video content from the DirecTV app or the U-Verse app is eligible, including on-demand TV shows and movies, an AT&T spokesperson said that most of that content will only be available for streaming in standard definition.

Data-cap exemptions, popularized in the US by T-Mobile's Binge On unlimited music- and video-streaming service, are controversial and have drawn scrutiny in the US. Opponents say the exemptions infringe on net neutrality rules, and that allowing carriers to exempt certain types of Internet traffic is a slippery slope to online censorship. In Europe, the exemptions are all but banned, following a recent update to the European Union's net neutrality regulations.

The fact that AT&T owns DirecTV also introduces an anticompetitive element to the debate, since the exemption could boost DirecTV signups.

As for mobile data, this is not the first time that customers of AT&T and DirecTV have enjoyed special treatment. In January, AT&T brought back its unlimited wireless data plan, but only for those who also subscribe to DirecTV or U-Verse.