Although video is increasingly used in public health education, studies generally do not implement randomized trials of multiple video segments in clinical environments. Therefore, the specific configurations of educational videos that will have the greatest impact on outcome measures ranging from increased knowledge of important public health issues, to acceptance of a voluntary HIV test, remain largely unknown. Interventions can be developed to run on affordable handheld computers, including inexpensive tablets or netbooks that each patient can use individually, and to integrate video delivery with automated data collection. These video interventions can then be used not only to educate patients who otherwise might not be reached, but to examine how content can be optimized for greater effectiveness as measured by cognitive and behavioral outcomes. This approach may prove especially valuable in high volume urban facilities, such as hospital emergency departments, that provide points of contact for lower income, lower literacy, and high-risk populations who may not otherwise interact with healthcare providers or researchers. This article describes the development and evaluation of an intervention that educates emergency department patients about HIV prevention and testing while comparatively examining a set of videos, each based upon competing educational theories. The computer-based video intervention and methodology are both highly replicable and can be applied to subject areas and settings far beyond HIV or the emergency department.