The study addresses professional vision, including the abilities of selective attention and knowledge-based reasoning. This article focuses on the latter ability. Groups with different sport-specific and pedagogical expertise (n = 60) were compared according to their observation and interpretation of sport activities in a four-field design. The first group (novice) was composed of student teachers who had their university studies and who were characterised by low sport-specific and low pedagogical expertise. The second group (athlete) comprised athletes with high sport-specific expertise determined by league affiliation. The third group (teacher) included teachers with high pedagogical expertise based on teaching experience and further pedagogical criteria. The fourth group (expert) consisted of teachers with high pedagogical expertise, who, in addition, played and coached basketball at a high level (high sport-specific expertise). Observational data were obtained from physical education classes. The participants' comments were recorded in a guided interview and analysed based on qualitative content analysis. The results were exported for further statistical analysis. The findings reveal general and specific differences in knowledge-based reasoning and identify different types of knowledge and beliefs used in this process. The implications for physical education teacher education programmes using video-supported reflection are discussed in light of the results.