"Film marketers have already been posting different versions of trailers on YouTube to work out which has the best response, but individuals can also optimise the popularity of videos by identifying the typical lifespan of a clip.This facility is of clear benefit to the creators of video clips for viral marketing purposes, as well as for advertisers who invest in the development of brand awareness but have few conventional means at their disposal - other than gross results in the marketplace - for working out how effective their spend on brand development, leverage etc actually is. An audience measurement tool that assists both brand owners and those whose services they pay for can only be a good thing.
New features will be added to the service shortly, including the time of day that each video is watched".
YouTube information on Insight here