The effects expected of video-analyses of lessons differ depending on whether videos of one's own lessons or videos of other teachers are being watched. The present study aims at systematically comparing the cognitive and emotional processes occurring when viewing these two types of videos. On the basis of key questions, ten math teachers commented on sequences from personal and third-party videos within the framework of a web-based learning environment. The case studies carried out subsequent to the qualitative and quantitative content analyses point to a stronger emotional involvement of teachers who were analyzing a third-party video. The emotions are positively correlated to an in-depth analysis of situations considered to be critical. Among those teachers analyzing personal videos self-worth-related emotions, in particular, impeded an in-depth reflection on such situations.