The Academic Technology Group at Harvard University has expanded upon its collaborative annotation tools so that they now include support for audio and video. Using the JavaScript API in JW Player, an open-source media player, we have enabled students to annotate selections of audio or video uploaded by instructors. Students and instructors can then search, review, and reply to annotations, thus generating threaded discussions. We currently have this new tool running as a pilot for Gary King, the Albert J. Weatherhead III University Professor, where he uploads a video preview of his lecture. Students then annotate sections of interest within the video, and the actual lecture focuses on these points of interest.