What Video Ad Length Is Best on Facebook? - eMarketer
It might be easy to assume that the shorter the video ad, the better the completion rate. But maybe things change when it’s on a social platform. According to Q2 data, video ads that were between 30 and 60 seconds long fared better than those of less than 30 seconds on Facebook.
6 Sep 2016 ... According to Q2 data, video ads that were between 30 and 60 seconds long fared better than those of less than 30 seconds on Facebook.