Although video analyses have a great potential for the development of professional competencies, the effects of (video-based) seminars on teaching activities and reflection competencies of student teachers have rarely been the focus of evaluations. In the quasi-experimental intervention study ProFee, the effectiveness of different seminar concepts on the competencies of elementary school student teachers in giving feedback was investigated. The evaluation focused on the question of how observation assignments and methods with varying degrees of structure affect students' competencies. After attending the seminar, the teaching activity of the N = 226 students did not differ significantly between courses when controlling for prior knowledge. But the students' self-assessments as well as the correlations between self-assessment and external-assessment are closer in the group in which the videos were analyzed in a very structured, low inferential manner.