The study inquired into the effect of research-based video-cases on pre-service teachers conceptualizing their understanding of contemporary mathematics teaching. The 43 participants enrolled in a Mathematics Method Course viewed and discussed 5 video-cases of primary teachers teaching. Journal entries, lesson plans, and microteaching observations were collected as data on which the following assertions were based. Pre-service teachers' responses to the 5 videos were more concerned with pedagogical content knowledge than mathematical content and students' learning. They refocused and deepened their awareness of students' learning and questioning skills through discussing the videos. The video-cases improved their construction of pedagogical representation and their ability to identify a problematic situation with multiple perspectives. These effects appeared to be influenced by the scaffold of three factors: vicarious experience to complement personal experience, watching and discussing video-cases enriched by the developers, and journal writing to foster deeper reflections.