Comcast, the country's largest cable company, says its tablet and phone app now lets subscribers download and store movies and TV shows from some channels for offline viewing.

Cable companies have rushed out applications that let viewers stream , but this is the first one that allows offline viewing. That's useful wherever there's no Wi-Fi signal, as cellular downloads are slow and can be expensive, given that video uses a lot of data.

.'s app won't allow downloads over cellular, except over ' "4G LTE" service. That's part of a far-reaching deal the company struck with Verizon a year ago.

The app allows the storage of movies and shows from Showtime, Starz, Encore and MoviePlex. They can be viewed for 14 days.