The usability of healthcare information technology has become a major issue in health informatics. There have been many reports of systems that have been deemed unusable by end users such as clinicians and a growing body of usability studies have been reported in the literature. The issue of how to fruitfully analyze and code usability study data in a meaningful way that can lead to optimized and more efficient systems has remained to be fully detailed. In this paper we describe our work in developing and organizing a principled video coding scheme that builds from our previous work in a couple of areas. We include video coding categories we have developed for understanding problems and issues with human-computer interaction. In addition, we integrate this coding scheme with categories we have used to characterize human cognition, such as clinical reasoning and decision making, in isolation of technology use. The resultant new scheme thus incorporates coding categories that can used to evaluate both usability issues (applying categories from human-computer interaction) and human cognition, in order to assess the impact of technology on clinical reasoning and decision making.