YouTube is changing the criteria used for ranking its videos. Earlier videos were ranked based on the number of clicks. Now the criteria is being changed to time spend by users for viewing these videos on the site.
Though YouTube subscriber base has increased, the time spent by the users on the site has been an area of concern for some time. It was made official that now onwards videos will be rated based on how long people are viewing them rather than on how many people viewed them. This would make videos who keep users engaged for a longer time will go up in rankings.
The change in ranking criteria will naturally change the way videos are promoted and it may need more aggressive promotional effort from creators as now ranking depends on how effectively they can bring in users and make them watch the whole video. Now a day promotion of YouTube video is done by giving a thumbnail image. This will no longer be effective as now ranking criteria has changed.
YouTube has put in place a time metric which shows how much time users have spent on watching YouTube video to help creators gauge the status of their videos in terms of where their video stand in terms of ranking.
It is clear that only those videos which are engaging and make users watch as a whole are going to remain popular and this would reduce the cheap publicity efforts of some creators to lure users to click rather than to watch.