Affecting preservice teachers' pedagogical intentions and future behavior is a challenging goal of teacher education. It may be accomplished by purposefully changing their beliefs. The aim of this study was to investigate whether lesson videos, compared to an argumentation-based video format, can evoke stronger and more positive emotional reactions and whether these reactions in turn result in higher changes in beliefs, attitudes, and intentions. We measured student-oriented teaching beliefs, attitudes, and intentions of N = 129 preservice teachers before and after the intervention. As a treatment check, we also quantified their emotional reaction (arousal and valence) to the intervention. Results of indirect effect models revealed that watching lesson videos led to higher emotional arousal and, overall, higher emotional arousal was related to more positive change in beliefs. However, change rates of teaching beliefs, attitudes, and intentions were the same for the lesson video and the expert talk video group. Emotional valence had no effect on change of beliefs, attitudes, or intentions. This study adds empirical evidence to theoretical claims concerning the effects of emotions on changing teaching-related beliefs.