Vaccine hesitancy was recently declared one of the ten greatest global health threats by the World Health Organization and research has linked it to low levels of health literacy. Health literacy can be supported by media literacy education which aims to heighten critical thinking and help individuals develop habits of inquiry and make appropriate credibility ratings to sources by increasing knowledge about various media, such as fake news, and its impacts. We describe the development of a novel educational narrative video (NV) we built on the fundamentals of media literacy education and the psychology of emotion regulation to help address this urgent societal problem and educational gap. In this article, we also evaluated the effectiveness of our NV in an online, longitudinal randomized control trial study examining how students in this condition performed on credibility accuracy ratings of media vignettes relative to students in a narrative text-based script (NT; modality control) and unrelated video control condition at (a) post-intervention and (b) follow-up time points. Findings indicated that low levels of epistemic emotions did not statistically significantly influence media credibility accuracy ratings. Surprisingly, students in the NV condition had significantly lower post-intervention accuracy ratings than those in the NT condition but the NV group had significantly higher follow-up accuracy scores. We contextualize these findings within media literacy education and the importance of advancing educational assessments beyond immediate post-tests, which have implications for researchers, educators, and organizations developing educational interventions.