Physical education (PE) teachers can be trained to adopt a more motivating teaching style, which includes providing autonomy support and structure. However, traditional training methods, such as in-person workshops with fixed schedules and locations, may limit these interventions' overall impact. Online video annotation tools, considering their flexibility and scalability, could serve as a useful addition to these existing training methods. We have developed a video annotation tool aimed at optimising the motivating style of PE teachers by encouraging self-reflection by watching and annotating classroom videos. In this chapter, we present results from multiple studies with our online tool, demonstrating its potential as an alternative or complement to traditional workshop-based interventions. For pre-service teachers, the tool was effective in reducing chaotic teaching behaviour. In-service teachers showed improvements in autonomy support, although the effects varied depending on the analysis method and informant perspective. These mixed results highlight the need for further research to refine the intervention and tailor it to the specific needs of each group. We conclude the chapter by discussing promising directions for future research on online video annotation tools, including the exploration of peer feedback and leveraging artificial intelligence to provide automated feedback.