Cite or Decline: A Strict Course-Grounded Chatbot for STEM Lecture Videos

A semester-long deployment of the VideoPoints platform with a retrieval-augmented chatbot for STEM lecture videos found that across 833 student messages, 70.5% included citations, none crossed a course boundary, and the chatbot usually declined to answer when no lecture evidence matched. The design improved correct-lecture retrieval by 6.3 percentage points over dense-only retrieval on the EduVidQA benchmark, with citations rated the most useful feature and practice-question generation the strongest unmet request.

arXiv:2609.01846v1 Announce Type: new Abstract: Recorded lecture videos, often enhanced with search and summarization features, are a standard study resource. However, students cannot easily ask course specific questions or verify answers against an instructor's lecture. We report a semester-long deployment of VideoPoints platform with a retrieval-augmented chatbot that answers from course lecture materials and returns timestamped citations. The chatbot retrieves only from the active course, uses chapter summaries to guide transcript ranking, and returns clickable timestamped citations. Students used it for quick lookups and exam review. Across 833 messages, 70.5% included citations, none crossed a course boundary, and when no lecture evidence matched, the chatbot usually declined rather than answering. Among the users, citations were the most consistently useful feature, while practice-question generation was the strongest unmet request. We also evaluated the design on the real-world test split of EduVidQA, a public multimodal benchmark for lecture-video question answering. Our design improved correct-lecture retrieval by 6.3 percentage points over dense-only retrieval. Together, the results show that effective deployment depends on course isolation, supported citations, and alignment with students' study practices.