That's actually not how it works. If you have a cable tv package nimble authenticates it and will let you stream live whatever you have access to for a small fee...$5? I think.
If you don't have a cable subscription, nimble signs you up for one through their dish network agreement. I believe they have some agreement with dish where they are allowed to resell access to 3rd parties. The cheapest plan being 29.98 a month and if you live in NYC or Chicago they throw in local broadcast stations for free. There are other tiers above that that will include more channels.
It's actually a pretty good, albeit more expensive replacement for aereo for me and actually includes more channels than aereo did.
For $29.98 on nimble I get 50 channels including all networks in HD with 20 hours of dvr; no contract required.
To get the same on TWC(the only provider available to me):
Time warner's starter tv is 20 channels for $19; hd dvr box is another $25 a month throw in taxes and licensing fees and I'm well over $50 and I am locked into a 12 month contract and I can't stream recordings without purchasing more hardware.