Adding questions to videos is a great technique to make sure students are watching and comprehending the video sources you are assigning to them. Edpuzzle and Zaption are two tools that let you add questions to specific points in your video timeline to check for understanding. Videos can come from a variety of Internet sites (YouTube, Vimeo, etc.) and you can trim the video to just the parts you feel are relevant.
This article provides a great overview of Edpuzzle and compares its features with Zaption to help you choose the best tool for your needs.