Nielsen Online has released statistics about the most popular social networking sites in the UK and their growth year-on-year:

Source: Nielsen Online, UK NetView, home & work data, including applications, Jan 2007 – Jan 2008
E.g. YouTube was visited by 10.4 million Britons in Jan 08, 56% more than in Jan 07

Three things I found interesting. First, huge growth for Facebook and a decline for MySpace – but this is a volatile market and Facebook may the the next site to beome less fashionable.

Second, the huge reach of these sites. Neilsen reckons that 20.8 million Brits visited at least one of these sites in January, representing 63% of those online.

Third, the growth of video. I think this is the most reliable long-term trend. You can see it more clearly in Neilsen’s figures for the fastest growing sites, five of which are video sites (vidShadow, Veoh, Youku (Chinese site), Tudou (Chinese site) and Video Jug), as well as in the rise of YouTube to first place.

Is the Internet moving towards video in the same way as traditional media (print -> radio -> TV)? Possibly.

There is a technical story here too. I’m at Mix08 this week, where Microsoft is promoting its Silverlight plug-in for video and rich visual content. However, all these sites currently use Adobe’s Flash plug-in, which will be hard to shift. Without the ubiquity and ease of installation which Adobe has achieved with Flash, I doubt we would be seeing this growth in video content.