In a move that could help cable operators pay the freight of "free" video-on-demand content, Nielsen Media Research said it will launch a new VOD measurement service on Dec. 11, 2006.

Nielsen said it will offer the new service by leveraging the same National People Meter sample it uses to provide TV ratings to national programmers. Like current rating methods, Nielsen's VOD clients will receive household and demographic ratings for VOD content alongside with other detailed audience information.

VOD titles prepped for audience measurement will use Nielsen-supplied "watermarking" audio codes, which will be applied to content with special encoding tools. Nielsen's new Active/Passive meters will use those watermarks to then identify on-demand viewing sessions.

Cable operators are already inserting ads into free VOD, and doing so dynamically in a few cases, but this new capability should also give them some important data that advertisers are looking for as they make a decision on whether to leverage the emerging on-demand delivery format.

Nielsen said the VOD measurement service, for the first time, will allow its clients to compare the performance of programs airing on traditional linear channels with the performance of those same programs offered via VOD.

Nielsen noted that the new measurements can be applied to older, library content as well as shows that have been recently broadcast.

"Because video-on-demand is a growing business and a potentially valuable new revenue stream for programmers, it is increasingly important for them to understand who is watching their shows and to be able to compare the viewing that is being done via traditional television and VOD," said Nielsen SVP Scott L Brown, in a statement.