Prior research has highlighted that for teachers to develop robust practices, they need to develop rich professional vision (PV)--the ability to see nuanced issues of teaching and learning in situ, interpret them, and respond. In the context of problem-based learning (PBL), PV involves guiding student-centered learning and understanding when to provide just-in-time scaffolding as students navigate real-world problems. In efforts between teachers and researchers to co-design PBL experiences, design partners co-construct PV as they put forth different ways of seeing and navigate how to support student learning together. We need to better understand how (1) PV is interactionally constructed in these efforts and (2) what tools and designs support this co-construction. We use discourse analysis to explore how joint video analysis in one co-design effort supported the simultaneous development of PV for teacher and researcher. Findings revealed that collaborative video analysis of classroom interaction and student artifacts acted as boundary objects for design partners--a shared space for meaning making. On video, classroom interactions were revisited, and alternative possibilities reimagined. Group artifacts (e.g., drawings and notes) made students' thinking available for interpretation. Consistent open-ended questions in co-design (e.g., "how are we seeing PBL in action here?") supported the negotiation and alignment of PVs, setting shared goals, and planning actions for upcoming class periods. This research contributes to our shared understanding of how to support research and practice that is responsive to local context and is mutually beneficial for researcher and teacher.