Zaption is an interesting interactive video platform developed by a San Francisco based tech start-up. It helps teachers use existing videos from YouTube, Vimeo and other sources to design interactive quizzes, coments, discussions... by creating a tour, in other words, a combination of these videos, images and text. Different types of questions are available (multiple choice, open response...)
On Twitter: https://twitter.com/zaption
On Facebook: https://www.facebook.com/Zaption
On Google+: https://plus.google.com/102766234496264824389
YouTube Channel: https://www.youtube.com/user/GoZaption/videos
Do you want to know how it works? Please, watch the following video.