That report (or, more likely, the way that the media have interpreted it) confuses correlation with causation.
It's unsurprising that people who spend a great deal of time watching TV having shorter lifespans than those who don't. But the cause is far more likely to be a simple lack of exercise than actually viewing too many episodes of East Enders! (i.e.. it's the fact that people are physically inactive which leads to shorter lives, not what they're doing during those periods of physical inactivity).
An analogy:
With teenage girls, there's a fairly high correlation between smoking and early pregnancy. That doesn't mean that smoking makes someone pregnant; it simply shows that girls who are likely to break 'rules' about smoking are also quite likely to ignore society's 'rules' about engaging in under-age sex.
Chris