Teaching practice and its representation by videos are a central part of many empirical studies concerning the field of teaching and learning. In order to analyze how videos can help to investigate aspects of teachers’ expertise, the data from 131 primary mathematics teachers who participated in the TEDS-Follow-Up study were evaluated. The teachers answered questions referring to scripted video-clips describing classroom situations. The questions were qualitatively analyzed covering the spectrum of aspects mentioned by the teachers and its relation to aspects of teachers’ expertise. The analyses showed that teachers notice and mention a great number of aspects that were either directly observable in the video-clip shown, or could be identified using the given information. In addition, it is pointed out that teachers with high professional knowledge notice possible reasons for a student’s error more accurately, while teachers with low professional knowledge focus on aspects that are not directly connected to the student’s learning.