In this study, we investigate how pre-service teachers' group dialogues emerged and intersected across time and space as students collaboratively constructed a video-based mind map to prepare for oral exams in a pedagogy course. The study was conducted as part of a design-based research project investigating the ways that video-based mind maps can support learning as both a collaborative activity and a classroom resource. We applied interaction analysis methods to recordings taken during the production of the mind map as well as the videos made by students within the mind map itself to analyze synchronous and asynchronous dialogues among group members as they viewed, recorded, and uploaded videos. The findings offer an in-depth understanding of how collaboration occurs in different space-time configurations within and across groups as mediated by video resources. We discuss how these findings contribute to computer-supported collaborative learning (CSCL) research on the ways collaboration can emerge across different levels of activity as well as the pedagogical implications for introducing video-based dialogues into the classroom.