A video mock-up is a "design story", described by Patrick Parrish in a recent "TechTrends" article as "imagining the journey of a learner's experience in engaging with a finished design". A design story allows designers to show their design vision to others and to observe features and benefits of the program as a learner would experience it. The design story concept has similarities to the "use case" technique developed for software and systems engineering to capture functional requirements. Use case scenarios depict in narrative form how the system should interact with users to achieve specific functions. Design stories add elements of setting, character, and plot. As Parrish suggests, design stories are valuable in both the formative evaluation (FE) and demonstration phases of multimedia product development. Video mock-ups used in the FE stage allow designers and subject matter experts to see the design features of the multimedia program in use. In this article, the author illustrates the decisions on which aspects of the multimedia design and learner interactions are central to the instructional success of the program by profiling two video mock-ups, one produced for formative evaluation purposes and the second for demonstration purposes. In both examples, the instructional multimedia program that is the subject of the video is first described in enough detail to explain the key design features and learner interactions. As described by Parrish, the value of the design story is to reveal--to the designers as well as to evaluators and clients--the essential learner interactions that define the deep structure of the instructional program. (Contains 8 figures.)