That is not that bad. I left Hulu HD running for 15 or 16 hours yesterday and it used a whopping 4GB or so. I can't separate out my other traffic usage, but the entire day was only 5GB.
and except for the very very few HD shows they have at most their shows and movies stream at a paltry 1 Mbps which is barely 480p. 720p quality shows/movies would run about 3 GB per hour. So 2 1/2 hours day would put you over the cap. If you have a family of 4 then each person only gets about 40 minutes a day. That's assuming you use your internet connection for watching online video and nothing else.
In the near future even a 1 TB cap is not going to be enough.
I know 1Tb will not be enough soon, right now it kinda is but in a few years we will need at least 2TB. Man I hope the cap dies. I don't care if the ISPs just drop it cause they see a way to get money from it or if it is because stuff like FiOS cablevision and other uncaped cablecos(or FTTH/other ISPs) force them to via competition(IMHO the best solution).