A new study by the NPD Group shows that peer-to-peer (P2P) digital video downloads reign supreme in the US, outpacing legal alternatives such as the iTunes Store by five to one.

What people are downloading is also an interesting point. The study said that among US households with members who regularly use the internet, approximately 8 percent - six million households, all told - downloaded at least one digital video file 10MB or bigger from a peer-to-peer service for free in the third quarter of 2006.

By comparison, about 1.2 million US households - about 2 percent of those households that regularly use the internet - paid for a video download from an online store. The iTunes Store was far and away the most popular source for legal video downloads - 90 percent overall. Vongo, Movielink and CinemaNow trailed iTunes.

Of the pirated content downloaded through peer-to-peer services, about 60 percent was adult film content, while 20 percent was TV show content and 5 percent was mainstream movie content.

Comparatively, legal downloaded content consisted about 62 percent of TV programme content, 24 percent of music video content and 6 percent of movie content, according to the report.

Russ Crupnick, vice president and senior industry analyst for the NPD Group, said that online video piracy is less pervasive than it is for music, but he called it a "crucial issue" for the film industry.

"Even though right now the majority of downloaded video content is adult-film content, the amount of intellectual property stolen from mainstream movie studios, networks, and record labels will continue to rise, unless strong and sustained action is taken to prevent piracy," said Crupnick in a statement.

"Paid usage could double or triple within the next year as more content comes online, consumers acquire more video-enabled players and movies are offered that consumers can actually burn to DVD," said Crupnick.