Learning to conduct interactive classroom discussions is a high priority for becoming an effective teacher, and most teachers view conducting productive classroom discussions as a complex undertaking. Because the dynamics of facilitating classroom discussions are multifaceted and hard to analyze in real time, there is a growing interest in how video allows preservice teachers to examine records of their practice to promote further growth. What prospective teachers actually take away from analysis of video, however, needs further exploration. In this study, we explored five preservice student teachers' beliefs about conducting discussions and probed the potential of videocase construction for supporting teacher learning by investigating the following question: "To what extent and how does making a videocase help preservice teachers investigate their facilitation of a subject-specific discussion?" Results revealed that by constructing and talking about their videocases, all five preservice teachers gained insights about how they lead discussions. Studying video excerpts and articulating what they saw in them provided a context for looking more closely at their own roles and student roles within their discussion. They also recognized the complexities of leading discussions and acknowledged particular areas that need improvement. The teachers used the metaphorical language of "guiding" their students down a pathway when they talked about leading classroom discussions. There were similarities and differences among teachers' conceptions of good discussions in English and science, and their notions of "guiding" were related to their subject matter goals. The study suggests, however, several areas that may require further attention in preservice teachers' preparation in leading discussions. Although the teachers expressed views of discussion that aligned broadly with disciplinary views in English or science, their language lacked specificity in what it means to develop varied interpretations of texts in English or consensus based on argument and evidence in science. More specific video analysis focused on subject matter goals and corresponding conversational elements may help preservice teachers develop more nuanced, sophisticated views of how particular types of social interaction have the potential to help their students reach specific subject matter goals. We conclude that investigation is needed on larger numbers of preservice teachers' videocase construction processes, and further inquiry is needed into how working with video analysis affects their actual performance in future discussion facilitation. (Contains 1 note.)