If instructors were to have students do assignments as videos delivered in YouTube, then it might be useful to give feedback on specific parts of the video. The Annotations tool, currently in beta has the capability where the video owner can give annotation privileges to other users by sending a link. That seems pretty nice. Likewise teams of students could use the annotations tool on early versions of the video as they are trying to make improvements in what they have. It is an interesting idea.
On the other hand, I’m still not understand the duration that the annotation stays up on the screen and it seemed the one I made appears at a time slightly different from the time where I stopped the video.