Objective Students commonly perceive gross anatomy lectures as difficult because they contain complex information that requires three-dimensional visualisation in order to be understood. Without prior preparation, a gross anatomy topic expounded via lecture can be cognitively challenging. Hence, this study aimed to investigate the impact of a pre-lecture activity in the form of viewing a video on students' lecture comprehension. Method A quasi-experimental study was conducted using 254 first-year medical students with no prior exposure to the lecture topic during the 2016/17 and 2017/18 academic sessions. The students from each batch were divided into two groups and exposed to different video material. Group A watched an action movie, while Group B watched an educational video related to the lecture topic. After 15 min, both groups attended a lecture on the gross anatomy of the heart, which was delivered by a qualified anatomist. At the end of the lecture, their understanding of the material was measured through a post-lecture test using ten vetted multiple choice true/false questions. Results Group B's test scores were found to be significantly higher than Group A's (p > 0.001, t-stats [df] = −4.21 [252]). Conclusion This study concluded that the pre-lecture activity had successfully provided the students with some prior knowledge of the subject before they attended the lecture sessions. This finding was aligned with cognitive load theory, which describes a reduction in learners' cognitive load when prior knowledge is stimulated.