To help you have an idea what its like I will start with a similar (ish) site that has been around a long time. Have you tried Brainpop? Brainpop is a website designed for young students to learn various themes through video animation followed by revision questions. The site is well designed, easy to use and the animations are incisive and entertaining. I highly recommend it, but its very expensive.
TED Ed, on first look, seems very similar, but much, much more. The 'more' comes in the form of being personally customizable. You have videos, and accompanying questions and tasks, but you also have a "Flip this Lesson section". This allows you to add your own titles, learning objectives, introductions, tasks and questions. Not only this, it allows you to add whatever video you want to focus on, regardless of whether or not it is on TED. I am sure that the guys who made the site can explain it better:
I am definitely going to try this out as soon as I can. I will post my results. I can do this because when you create your own "Flipped Lesson" you get your own URL for that specific lesson.
However, that's not all!!!
It seems there is a section to record the responses of the students who look at your TED Ed lesson. I'm not sure if this means that they have to sign in or not, lets find out.