User-centered analysis can benefit the development of interactive video digital libraries. Findings from this study support the idea that having additional understanding about the intended users of video digital libraries can help researchers match system designs with the envisioned use of prototype systems. This study examines one user-centered factor specifically, familiarity with visual search topics, to explore if and how this may be associated with other factors within an interactive video retrieval context. Twenty-eight users from the field of science education were recruited to complete six visual search topics using a prototype system to retrieve video clips from a collection of NASA Science Education Programs. Analysis revealed that topic familiarity was associated with other factors that were examined throughout this study, including user-assessed and experimenter-assessed topic completion ratios, opinions of the prototype system, and interaction behaviors. Such results can have a variety of implications for developing video digital libraries, especially those designed to support queries and interactions of knowledgeable users from a defined domain.