You can watch cable TV online with that subscription if you're away from home or someone else is using the TV. There are a lot of popular streaming services that require a cable TV subscription to use: HBO Go, AMC, FX Now, and watchESPN, just to name a few. Some of them support just about every cable company, while others only support a few, so this could be a deciding factor if you're lucky enough to have a choice of cable companies.
Best companies to watch cable TV online
This chart displays what popular online video sources work with the largest cable TV providers in America. There are many other smaller online video services, and many smaller cable providers as well. Many cable companies are working to add support for new services. The chart is current as of May 8, 2014.
Comcast and AT&T U-Verse are the only two major cable providers that provide access to all of the different online video services listed. The big two satellite companies and some of the smaller cable providers are missing some key services.
Keep this in mind the next time you're shopping around for a new cable provider. Having access to live sports and shows on-demand through your smartphone, tablet, or PC is a nice perk that comes with that cable TV bill.