Just collating some tools for the above purpose, I hope to help an academic here create an online authoring/mashup tool of pre-rendered videos, audio-video interviews and images so that an audience particularly children can create their own narratives and presentations using the online multimedia archive (yet to be uploaded).

Leading contender

• http://popcornjs.org/ OR http://www.webmonkey.com/2012/11/mozillas-popcorn-maker-brings-video-remixing-to-the-masses/

Looks interesting

• http://www.magisto.com/how-it-works
• http://www.masher.com/
  https://www.wevideo.com/ for mobile
• http://mashable.com/2007/06/15/youtube-remixer/#HlUkuwU7EPqi

Other

• http://mashable.com/2007/05/31/gotuit-powervideo-suite/#6549jF41cEqr Gotuit Launches the PowerVideo Suite
• http://mashable.com/2006/11/07/mojiti-annotates-clips-from-youtube-revver-google-video/#a7jx48jlU8qa

Other video remixers

http://mashable.com/2006/03/07/eyespot-all-hail-the-video-mashups/#rwZQ_lZ8Umq8