Research in mathematics education has placed significant emphasis on teacher identity, particularly during teacher education, since it plays a critical role in shaping the identity of preservice teachers with regard to teaching mathematics. However, as teacher identity is context dependent, it is essential to study preservice teachers' identities in various contexts to develop expertise in mathematics teacher education. This study explored the transformation of preservice mathematics teachers' (PMTs) teacher identity orientations after participating in a video club. Concentrating on task perceptions as the indicator of teacher identity, the change in the teacher roles that PMTs would like to adopt in the future and the student outcomes they associated with these roles were investigated. The analysis of teacher identity orientations before and after participating in the video club revealed that PMTs' teacher identity orientations were transformed by their participation because the video club increased their self-awareness and understanding of the complexity of teaching mathematics. The most noticeable transformation was observed in the didactical roles and their associated outcomes. These roles were transformed from being a didactical expert aiming to develop students' affective outcomes to being a didactical expert who prioritizes students' cognitions. Although PMTs' expertise in teaching mathematics and the content of the video cases limited their orientations, the video club can simulate alternative experiences for teacher education programs aiming to support PMTs' teacher identity orientations.