The BBC's iPlayer service continues to prove extremely popular with UK viewers, according to media analyst Screen Digest.

A surge in iPlayer use has prompted Screen Digest to improve its forecasts for free-to-view (FTV) consumption in the UK to better reflect the emerging importance of the model in driving web TV services.

UK broadband households initiated some 800 million FTV online streams and downloads in 2007, including TV shows, sports and niche programming, and the bbc.co.uk domain, including the iPlayer sub-domain, accounted for 38 per cent of the total.

Screen Digest predicts that the streams will rise to 1.5 billion in 2008 and 2.8 billion by 2012.

The analyst firm reckons that the iPlayer's success underlines a comparative lag in other broadcasters' delivery models, and emphasised two major factors in determining a successful free online video proposition for broadcasters.

The first is the BBC's decision to migrate the iPlayer's focus away from a proprietary application download environment to an open access web streaming model which coincided with a significant rise in online viewers.

Screen Digest believes that the application-based strategies pursued by some UK broadcasters puts up an unnecessary barrier to initial consumer adoption, thereby hampering growth.

Secondly, moving to a Flash-based streaming platform offering full seven-day catch-up has been a critical move by the BBC, as it allows non-Windows users to access programming as well.

The corporation was heavily criticised for this lack of compatibility when it started the iPlayer service.

"Our long-term financial outlook for the UK online TV sector will now depend on the future development of convincing platform strategies by ITV, Channel 4 and Five, as well as new entrants such as Bebo, MySpace, YouTube and Joost," said Arash Amel, senior analyst at Screen Digest.

"It is expected that the success of the BBC's open web streaming model, and future 'viral syndication' strategies, will encourage UK commercial broadcasters to enter a long-term reassessment of how they deliver programming to users."

Over a million viewers used iPlayer to download or stream over 3.5 million programmes during the fortnight before Christmas.