Nielsen's video-measurement tool tracks the average time spent watching videos, and records demographics in addition to total numbers.
It has won approval from the Online Measurement company (UKOM), run by the IAB and Association of Online Publishers (AOP). The first UKOM-approved data will be out in July.
Ben Mein, Nielsen commercial director, said: "Web video is increasingly important as a communications channel and with Nielsen VideoCensus, they now have an industry-endorsed product which allows them to know who, when, where and how people in the UK engage with web video."
For brands and agencies, the tool will give figures for duplication of audience in addition to demographic data, and should show which time slots offer the most valuable target viewers.
Publishers will be able to find figures for full audiences and compare themselves with competitors.
James Smythe, UKOM general manager, said: "Video-on-demand [VoD] audiences have been growing rapidly, driven by broadcaster investment and platform development.
"To support the VoD advertising model, the industry needs reliable, people-centric measurement, especially with demographics to line up with traditional TV. Nielsen VideoCensus is a hugely important step forward in the measurement and understanding of TV audiences."
UK Unique visitors: number of people visiting video sites (000s) April 2011
Source: Nielsen VideoCensus
The first set of figures, covering April 2011, shows that YouTube is by far the most visited digital media video site with 19.5 million unique users – more than two-thirds of the total UK figure of 29.6m unique users – followed by the BBC, visited by 9.1 million unique users, Vevo with 5.4 million, and Facebook with 4.4 million.
In addition, YouTube was the destination of choice for two-thirds of all online video streams in the UK. Of 2.19 billion streams, 1.48 billion (67%) were watched on YouTube.
For average streams per unique viewer, YouTube was also the market leader, with each viewer watching an average of 75.7 streamed videos in April, followed by Channel 4, Megavideo and Dailymotion.
The data also shows that men watched 1.398 billion streams, compared to just 795 million for women.
Total UK video streams: number of streams viewed (000s) April 2011
Source: Nielsen VideoCensus
People spent the most time in total watching YouTube videos, with 2.79 billion minutes (5,300 years) of content viewed in the UK in April 2011.
The only measure where YouTube was beaten was time spent per site. TVCatchUP was the longest-watched site, with 337 minutes watched on average per month, followed by Bleachget, Megavideo, and then Youtube in fourth position.
Google was rated as the number one online brand by Nielsen in March.
.jpg)
.jpeg)