<p>The presence of on-screen instructors in educational videos, as well as the contextual conditions surrounding their use, constitutes a critical aspect of instructional video design. Variables such as the type of instructor – whether a human presenter or a pedagogical agent – and the characteristics of the knowledge type affect learning outcomes. However, the literature remains inconclusive regarding how the presence and presentation style of on-screen instructors influence learning outcomes across different knowledge types. Therefore, this study investigates the impact of an instructor’s presence in educational videos on learning outcomes, mental effort, and visual attention allocation, with a focus on the knowledge domain. A three-by-two between-subjects factorial design was employed, with video type (no on-screen instructor, human instructor, animated pedagogical agent) and knowledge type (declarative, procedural) as the independent variables. A total of 160 university students participated in the study. Results indicated that instructor presence influenced retention and visual attention allocation depending on the knowledge domain. Procedural knowledge videos led to higher transfer scores and mental effort than declarative ones. Importantly, however, the presence of an on-screen instructor – whether human or a pedagogical agent – did not produce differences in mental effort or learning transfer. Both human and animated pedagogical agent drew learners’ visual attention, potentially dividing it between the instructor and the learning content, whereas videos without instructors directed visual attention more exclusively toward the content itself. These findings highlight the importance of knowledge type in determining the effectiveness of on-screen instructors, suggesting pedagogical agents as viable alternatives to human instructors.</p>