COVID-19 has severely impacted the world since December 2019, and because of its highly infectious nature, many countries around the world have taken lockdown measures to prevent the virus from spreading unchecked, resulting in ramifications for higher education as many institutions have been forced to implement distance education. The question of how to develop a teaching method suitable for teacher education programs that place particular importance on practice in classroom settings warrants particular concern. Online video-based simulation training (OVST) as a teacher training method holds promise for addressing this issue by allowing learners to increase their opportunities to apply theory-based knowledge in real educational practice, reducing the theory-practice gap. OVST can also be distributed through online learning environments that offer easily repeated large-scale usage at lower cost to a variety of introvert/extravert learners through individual learning trajectories. In this vein, this study aims to introduce a method for developing OVST used to enhance pre-service teacher competence (by immediately intervening during school bullying, or CIISB) and clarifying the efficacy of types of OVST (with and without debriefing) on strengthening pre-service teachers’ CIISB skills. A total of 98 pre-service teachers from four Taiwanese universities and colleges participated in this study that adopted a quasi-experimental design approach. Each of these pre-service teachers was assigned to one of three groups: OVST with debriefing, OVST without debriefing, and an OVST control condition, with a video-based instrument used to map pre-service teachers’ CIISB-related perception, interpretation, and decision-making skills (PID skills). The results of a mixed-model two-way ANOVA analysis indicated that both types of OVST were more effective than the control condition in improving pre-service teachers’ CIISB. OVST with debriefing was also more effective than the OVST without debriefing, suggesting that OVST with debriefing is a promising way to develop pre-service teachers’ clinical competencies, while also offering a valuable resource for teacher education training methods, particularly when conducted under pandemic conditions.