EdPuzzle is a neat tool that I recently learned about from David Kapuler. EdPuzzle allows you to add your voice and questions to educational videos. On EdPuzzle you can search for educational videos from Khan Academy and Learn Zillion. Once you've found a video you can insert your own voice comments. You can also create a series of questions to go along with your chosen video. Questions are inserted along a timeline that matches the video. That means that your students don't have to wait until the end of a video in order to answer the questions. In that regard the EdPuzzle is similar to Blubbr.tv.
Applications for Education
EdPuzzle could be a good tool to use to create short review videos or flipped lessons for your students. You could also have students use EdPuzzle to annotate videos by pointing out important aspects of videos by using the voice comments option and or the question building option.