In just one month, DirecTV Now managed to attract over 200,000 paid subscribers. That's according to an SEC filing from DirecTV's parent company AT&T (NYSE:T).

Those subscribers indicate relatively rapid adoption compared with competing streaming services such as DISH Network's (NASDAQ:DISH) Sling TV and Sony's (NYSE:SNE) PlayStation Vue. It's also more subscribers than Comcast -- one of the few cable companies actually adding subscribers -- added over the last four quarters combined.

Language in AT&T's filing indicates that all of its video subscriber growth came from DirecTV Now, which puts a lot of pressure on it to continue growing.

How 200,000 net adds compares to the competition

Nailing down the details of other streaming services such as Sling TV and PlayStation Vue is tough. DISH Network now lumps Sling TV subscribers in with its satellite TV subscribers, but it did provide a glimpse at Sling TV's early results.

After launching in early February 2015, Sling TV had managed to attract just 169,000 subscribers by the end of March 2015. One year after its launch, The Wall Street Journal reported total Sling TV subscribers had topped 600,000. The service is still adding subscribers at a steady pace, however, with an estimate from October saying Sling TV had topped 1 million subscribers.

Sony's PlayStation Vue has fewer subscribers. It reportedly managed to surpass 100,000 subscribers over the summer, three months after its nationwide launch. It had operated in select markets for about a year before its nationwide launch.

Can it continue?

DirecTV Now's stellar results may be largely driven by its limited-time promotions. For the first month and a half, DirecTV Now offered subscribers a bundle of channels normally priced at $60 per month for just $35 per month. That price is locked in for life, too, with the company reserving the right to raise the price if its costs go up. It's also offering free hardware, including an Amazon Fire TV Stick or Apple TV for customers willing to commit to just one month or three months, respectively.

AT&T and DirecTV also did an excellent job of building anticipation for the product. That may mean the spike in sign-ups could be short-lived, as those 200,000 subscribers represent months of pent-up demand. What's more, users have complained of severe technical difficulties, which may lead them back to other options, such as Sling, Vue, or traditional pay TV. It's extremely likely DirecTV Now signups will slow, and if it doesn't add key features such as a DVR, the pace may fall considerably as subscriber losses offset new signups.

What this means for AT&T

The wording of AT&T's SEC filing is rather telling of the importance of DirecTV Now to its pay-TV operations. AT&T saw "more than 200,000 video net adds, entirely driven by DirecTV Now," it wrote. That language implies that the combined net adds of AT&T's DirecTV satellite and U-Verse was zero.

That jibes with AT&T's results since the company acquired DirecTV. AT&T has failed to grow its overall subscriber base in any quarter since the acquisition, as it focuses entirely on growing DirecTV while it loses hundreds of thousands of U-Verse subscribers. Over the past four quarters, AT&T has lost a total of 132,000 video subscribers between the two products. The third quarter was its best since the acquisition (not including the most recent quarter), losing just 3,000 subscribers.

AT&T is making a big bet on DirecTV Now to drive its video subscriber growth. While the early numbers are extremely encouraging and much better than its main competitors at this point in their life, there are still questions about its ability to continue growing.