“Netflix is killing illicit filesharing” is the way a new study has been spun in some quarters. But closer inspection doesn’t entirely bear that out.

The study is the latest in a regular series by Sandvine. It’s combined data from a a range of internet providers.

The figure that’s getting the most attention is Netflix making up 31.62 percent of North American traffic, followed by YouTube on 18.69 percent, HTTP use (that is, web page browsing) on 9.74 percent, BitTorrent on 4.05 percent and iTunes on 3.27 percent.

There are two very important points to note however. One is that the data only covers peaktime traffic, meaning evening hours local time. The other is that it is downstream traffic only. BitTorrent still dominates upstream traffic at 36.5 percent, ahead of HTTP on just 6.03 percent.

Combining downstream and upstream traffic, Netflix remains top at 28.17 percent followed by YouTube on 16.78 percent, HTTP on 9.26 percent and BitTorrent on 7.39 percent. Sandvine notes it’s the first time BitTorrent and other peer-to-peer services have dropped below 10 percent overall, falling from a peak of 60 percent.

The theory that people are turning to Netflix in place of pirating movies and TV may have some validity, but it’s not necessarily as clearcut as the figures success. For one thing, the figures are percentages rather than raw data size, and the overall amount of data people use is rising at around 20 to 30 percent a year. Sandvine estimates the mean average customer is downloading around 37.9 GB a month, though with the median average at 15.6 GB it’s clear a minority of users are hammering their connection.

Another limitation is the figures being based on peak periods. By definition, video streaming has to be done at the time the viewer wants to watch, which will most often be evenings. By contrast people using peer-to-peer to share files may do so at other times of the day for convenience, to get better speeds, to make sure a large file is ready for evening viewing, or because of “traffic management” policies that restrict peak time downloads.

Still, even if the “trend” may be exaggerated, it is clear that Netflix and YouTube continue to be responsible for a sizable proportion of Internet data use in North America. That could mean continued efforts by internet providers to bypass the net neutrality principle and seek to either restrict traffic to such services, or try to find ways to make Netflix and Google contribute more towards the costs of handling the data.