From an overview of a service Comcast evidently doesn't really want to sell, based on features and comparisons with traditional Internet + TV bundled services; tangentially, see Netflix Soars to 65.6 Million Subscribers as New Shows Shine (BloombergBusiness)
"But while Stream will let you watch recorded shows and movies using any broadband connection, it lets you watch live TV only when you’re connected to the Internet in your home. It’s mobile TV for people who don’t move.Is Comcast’s Stream too shallow? - Business - The Boston Globe
Don’t blame Comcast; they’re bound by the TV networks, which are in no hurry about bringing their live shows to the Internet. For instance, ABC and NBC currently stream their shows live in several cities, including New York, Los Angeles, and Chicago, but not Boston. CBS’s new All Access service delivers that network’s live shows, but charges $6 a month to view them.
A Comcast executive told me they’re in talks with the networks and hope that, by year’s end, Stream subscribers will be able to view network TV shows wherever they like."