Dears optimistics, and more precisely the webcontent' managers ones, here it is a tool than can change your live in video publishing. In fact this tool give you the opportunity to add content, onto layers, on an existing youtube video by exemple. Short video better than a long speech, try it by yourself !
https://popcorn.webmaker.org/
"Video beyond the box. Popcorn Maker makes it easy to enhance, remix and share web video."