Aiming to increase ad exposure to reticent video viewers, Google's YouTube made a quiet update to its year-old InVideo ad program. If users don't click to view an overlay unit accompanying a video, YouTube now runs the ad as a post-roll.

Not all ads will have the video option, according to a YouTube spokesperson. Those that take the viewer to a brand channel or external site, for example, will not play a video at the end. Unfortunately, only about four percent of YouTube videos — those uploaded by official partners with revenue-sharing agreements — have ads, whether they be pre-roll, post-roll, or overlay, writes NewTeeVee.

Last year, YouTube users voiced concerns about advertising on the video site, citing lack of creativity and loss of user control. In June YouTube enabled content producers to sell ad space across their own channels and in videos.