MoocNote is a good tool for adding time-stamped notes to the videos that you watch. You can also use it to create time-stamped questions for others to answer while watching a shared video. MoocNote works with videos from YouTube as well as videos that you import from Google Drive or Dropbox.
The latest update to MoocNote introduced a Chrome extension for taking notes and answering questions while watching a video on YouTube. With the extension installed you don't need to open the MoocNote site in a separate tab or window.
Applications for Education
MoocNote includes an option for creating groups or classes. You can create public or private groups with which you share your video lessons. You can arrange all of your videos into courses then share those courses with the group. If your course is a work in progress, you can add to it as needed and everyone in your group will see the additional content as you add it.