Online video viewing is up by over a third in the last year. YouTube dominates, with over two billion views a day, but its overall share of online viewing is falling. In the United Kingdom, despite the success of the BBC iPlayer, broadcaster sites accounted for just over 4% of the 5.5 billion online videos viewed in February. Aggregator SeeSaw reportedly attracted only 50,000 video viewers in its first full month of operation.

In the United States, nearly 175 million online viewers watched over 28 billion videos in February, comScore Video Metrix reported. YouTube accounted for 42% of them, averaging 94 videos per viewer. Hulu was the next most popular site, with 912 million videos and a 3.2% share, followed by Microsoft with 622 million and Yahoo! with 454 million. These four sites together accounted for half of all videos viewed.

Hulu had almost 40 million unique viewers, watching an average of over 23 videos each, clocking up 2.4 hours per viewer.

In March, Hulu served over a billion videos, with an average of over 26 videos per viewer, watching over 2.6 hours a month. That works out at 5.8 minutes per video, compared to 4.3 as an average across all online video.

In the United Kingdom, around 5.5 billion online videos were viewed in February, compared to just over 4 billion the same month the previous year.

YouTube accounted for 45% of all online videos viewed, down from over half of them a year before.

The BBC was the next most popular online video service, with almost 140 million videos viewed, accounting for 2.5% of the total, up from 1.5% the previous year.

This was followed by video sharing site Megavideo, Facebook, Microsoft, Channel 4, Dailymotion, ITV, Blinkx and Sky, ranging from 1% to 0.4% of videos viewed. The top ten sites accounted for over half the videos viewed.

Facebook and Blinkx recorded the greatest growth, up over 200% on the year, while the broadcasters more than doubled their video traffic.

Viewers on BBC sites watched 15.7 videos a month on average, compared to 13.5 for ITV and 18.8 videos each on Channel 4 sites.

SeeSaw, the aggregation site operated by Arqiva, attracted just 50,000 video viewers in March, the first full month after its launch. Visitors streamed an average of 12 videos, watching for 8 minutes in total, according to comScore estimates as reported by Broadcast magazine. SeeSaw suggests the service has far more viewers but has not offered any figures.

Some £5 million will apparently be spent on advertising the SeeSaw service but this must be measured against the invaluable on-air promotion that broadcaster services receive.

The comScore figures based on a survey panel methodology are widely reported and accepted but may not accurately reflect actual usage, particularly for sites attracting small percentages of total video traffic.

The BBC itself reported 68.7 million online video requests for the iPlayer in February, with 4-5 million unique users a week. This figure is based on a 25% sample of its server logs and only includes viewing identified as from within the United Kingdom.

In comparison, comScore reported 140 million videos viewed on BBC sites. That could include other videos, such as news clips. If only the iPlayer viewing is counted, as reported by the BBC, it represents around 1.3% of all online video viewing in the United Kingdom as estimated by comScore.

However one measures it, online video viewing is still overwhelmingly dominated by short clips rather than full programmes on broadcaster and aggregator services.

While YouTube continues to grow spectacularly, its share of all videos viewed is falling relative to the online video market in general, which is expanding at an even faster rate.