I've followed with anticipation each time over the years - a new website allowing teachers to make comprehension quizzes for Youtube videos. As the director of Education at EnglishCentral, this is interesting to me because EnglishCentral is working on similar functionality.
There is a long list of sites doing this, going back to ESL Video and Mystudio (now Quiz Revolution) and more recently TED ED Each has/had their own strengths and weaknesses but none of them I ever felt had what it takes to really get this user generated application to be the "full monty" and extremely useable widely by teachers.
I was able to make the 5 question quiz fairly easily but ran into some difficulty with dragging the buttons at the bottom and figuring out how that works. Watch out for that if you make one. Except for this I find it having the most potential of any youtube quiz maker. It has an attractive interface, is well laid out and designed and the library is very accessible. One downside - it doesn't allow you to edit the quiz after you've produced it (usually the case with just launched sites). I'm sure they'll work things out.
All in all a welcome addition to the video quiz world and I'm looking forward to seeing the changes they make - right now it won't get wide use by teachers but with a few well thought out changes - Blubbr could!