Netflix on "auto" quality settings, watching "Weeds" for a minute, translates to 60 GB/month (per 1 hr/day). We quickly dialed that back to the middle setting.
YouTube is about one-tenth of that, for regular quality video. HD was triple the regular amount (but it will depend on what you watch). So, 6 GB/month (per hour watched/day) for standard quality. 18 GB/month (per hour watched/day) for High Def. YMMV.
In Sandvineâ(TM)s 2014 Global Internet Phenomena Report, the group found that people exhibiting cord-cutter behavior -- those people who had a significantly high amount of streaming media consumption -- the average consumption amount was 213GB per month.
That is our household in a nutshell -- cord cutters. The teens watch zero TV. Same for my spouse. I use TV mainly for sports, and new Top Gear episodes. No ISO downloads, no torrent use at all.
Honestly, I'm a bit surprised by our usage. I'll probably install some program to track it for a while and figure out who and what are the biggest users.
From that page, "Google says that the video site reaches almost one out of every two people on the Internet."
"one of every two" -- so, every other household uses YouTube. When it hits 51%, that would mean the average household uses YouTube.
Comcast's "20 or 25" as an "average" figure is...unlikely.
FWIW, our household of four uses an average of 350 GB a month. Despite Comcast's claim that the average account uses 20 to 25 GB a month.