Teachem is a new service that is using the TED Ed model of creating lessons based on video. On Teachem teachers can build courses that are composed of a series of videos hosted on YouTube. Teachers can write questions and comments in "flashcards" that are tied to specific parts of each video and display next to each video. Students can take notes while watching the videos using the Teachem SmartNote system.
You can create a sample course in Teachem to try it out, although you do have to create a free account. Note that students/participants also need a free account to write notes. Making a sample course is a straight-forward process of adding a video URL then typing out questions. When you create a Teachem course you can make it public or private. Public courses can be accessed by anyone that has the address for your course. Public courses are supposed to be discoverable on Teachem, but finding any courses that you haven't created does not seem to be straightforward.
For comparison - note there are other similar tools - see scoop.it items on this page - Grockit answers and Vialogues.
Thanks to @richardbyrne for this resource from his blog Free Technology for Teachers http://www.freetech4teachers.com
My rating: 8/10