I would like to know, if there is such a thing like "quiz as video overlay" in moodle some where?
http://player.kaltura.com/docs/index.php?path=LimeSurvey
This looks interesting.
Closer to moodle is the already very advanced tool CAPIRA
If you use Camtasia, you can insert questions into the video itself, then export it as a scorm package and bring it into Moodle. The quiz questions will automatically be added to the gradebook.