Visual perception principle of watching video is crucial in ensuring video works accurately and effectively grasped by audience. This article proposes an investigation into the efficiency of human visual perception on video clips considering exposure duration. The study focused on the correlation between the video shot duration and the subject's perception of visual content. The subjects' performances were captured as perceptual scores on the testing videos by watching time-regulated clips and taking questionnaire. The statistical results show that three-second duration for each video shot is necessary for audience to grasp the main visual information. The data also indicate gender differences in perceptual procedure and attention focus. The findings can help for manipulating clip length in video editing, both via AI tools and manually, maintaining perception efficiency as possible in limited duration. This method is significant for its structured experiment involving subjects' quantified performances, which is different from AI methods of unaccountable.