Nielsen's term, "Zero-TV," covers households that receive the majority of their television programming from devices other than a TV set, such as computers, tablets, smartphones, etc. (It doesn't, however, imply that the home has no TV set.)
As the chart shows, close to half of the "Zero-TV" households are young -- under age 35. This makes perfect sense, what with the expensive prices of cable packages and the relative affordability of streaming episodes of choice on sites like Amazon Instant, Hulu Plus, iTunes, Netflix and more. And let's not forget about HBO GO password sharing -- something cabler HBO is considering addressing with the possible addition of GO services to internet packages.