This is a great resource that covers all assets of video production. I find that a number of my students come across this resource on their own every year when studying for quizzes or needing a quick refresher on any given topic. Contains many great photos and examples as well. Quizzes are available for teachers who would like to take advantage of that option.
3-12
Teachers and students can create or search voicethreads. Images, videos, documents can be uploaded and students can collarborate and/or add comments to voicethreads.
Cons: must register and limited access for Free version.