According to a new report from Nielsen, the number of U.S. homes that have broadband Internet, but only free, broadcast TV, is on the rise. Although representing less than 5% of TV households, the number has grown 22.8% over the past year.

In addition, the behaviors within these homes are unique. These broadband/broadcast-only households stream video twice as much as the general population, says Nielsen, and they watch half as much TV.

Nielsen hesitates to dump all these households in the “cord cutters” bucket, though, saying that while perhaps some are cord cutters (the term that refers to those who gave up cable TV for streaming TV/streaming video), other homes may be former broadcast-only homes that now have upgraded Internet service. Even though the exact percentages are unknown, combined, this two groups are making up the small, but growing demographic of Internet TV watching homes without paid TV.

Roughly the same percentage of consumers in this new and growing group of U.S. TV households watch traditional TV, stream or use the Internet as in all the cross-platform homes, but the difference is the time spent on these activities.

The broadcast-only homes spent 122.6 minutes per day watching TV compared with cross-platform homes’ 265.5 minutes. Not surprisingly, they stream more video, at 11.2 minutes per day vs. 5 minutes for the traditional households.

Those streaming numbers are interesting, however. Neither household (traditional or broadcast-only) is streaming the equivalent of even a sitcom’s worth of television. In other words, the Internet may not be just a new medium for TV to travel over, it’s an alternative to TV watching entirely.

Specifically, younger Americans are growing up involved in different activities beyond staring vacantly at the TV screen, it seems. Those aged 12 to 34 are spending less time in front of the TV (120.56 monthly minutes), but those older than 35 are spending more. And those over 55 watch the most (195.10 minutes per month).

Overall, few TV households are willing to give up the luxury of either TV or the Internet, regardless of how they choose to view either medium. The vast majority of TV households (90.4%) still pay for a TV subscription, and roughly tw0-thirds (75.3%) pay for broadband. The percentages of both have remained stable, despite the down economy. In fact, the number of homes paying for both a subscription and broadband has even increased by 5.5% over the past year.

TV viewing isn’t just being impacted by the Internet, Nielsen found. From Q3 2008 to Q3 2011, the number of those watching time-shifted TV has increased by 65.9%, and mobile video viewing has seen a 205.7% increase in users. Meanwhile, watching TV on the Internet has increased by just 21.7% during the same time. What these numbers show is that the issue isn’t as simple as switching from one medium to another (traditional TV to video on the laptop, e.g.), but that there are today a plethora of new TV consumption choices. Americans are experimenting with finding the mix that’s right for them. And that mix may not even be consistently applied by every member under the same roof.