Lesson study (LS) is a process through which teachers design, teach and discuss a lesson collaborating with colleagues. Sometimes, it includes video recording the lesson so teachers can use videos to later discuss the lesson and its improvement, however, there is little research addressing the consequences of doing it. This article investigates participants' perceptions and use of video within LS. Results show that participants perceived video in LS as viable and with potential to stimulate reflection and to improve lessons, but also evince that video affects the outcomes, management and sustainability of LS. We analyze and discuss its potential and the challenges it poses, suggesting ideas for its implementation.