DynamicSlide

Slide-based video is a popular format of online lecture videos. Lecture slides and narrations are complementary: while slides visually convey the main points of the lecture, narrations add detailed explanations to each item in the slide. We define a pair of slide item and the relevant sentence in the narration as a reference. In order to explore the design space of reference-based interaction techniques, we present DynamicSlide, a video processing system that automatically extracts references from slide-based lecture videos and a video player leveraging these references. Through participatory design workshops, we elicited useful interaction techniques specifically for slide-based lecture videos. Among these ideas, we selected and implemented three reference-based techniques: emphasizing the current item in the slide that is being explained, enabling item-based navigation, and enabling item-based note-taking. We also built a pipeline for automatically identifying references, and it shows 79% accuracy for finding 141 references in five videos from four different authors. Results from a user study suggest that DynamicSlide's features improve the learner's video browsing and navigation experience.