With an increasing number of videos integrating instructor's visuals on screen, we know little about the impacts of this design on mind wandering. The study aims to investigate a) how instructor visibility impacts mind wandering; b) the relationship between mind wandering and retention performance; c) how visual behaviour during video-watching influences mind wandering. Each participant watched a video with or without instructor visibility, while their visual behaviour was recorded by an eye tracker. Retention performance was measured at the completion of the video. Mind wandering was inferred via global self-report measure and objective eye tracking measure. Both measures of mind wandering indicated the instructor visible video resulted in less mind wandering. Findings suggested mind wandering impaired retention performance. Additionally, visual attention to the instructor was associated with less mind wandering.