Cox does that too, i got a warning email a few weeks ago....apparently its not really enforced though according to people ive talked to. Id imagine Comcast is similar I imagine it will be automatically enforced. On the bright side, I believe I read I get three overages in a 12 month period (not sure when this period started) for free, so I guess I shouldn't worry too much. My account page shows my last three months' usage and the most I used prior to August was 201 GB. I think this month was a combination of heavy Brewers game watching online and my wife's binge-watching of both Orange is the New Black (which I watched, as well) and Scandal (which I only partially watched). Once baseball season is over, I can't imagine I'll come close to the cap.