Lessons are defined as one object. Lessons are often bite size bits of customized content to meet the needs of your audience. These are not really lessons, they are preached pieces of content with a static audience in mind..
There are various video creating, editing and sharing websites already available for teachers. Most content of much value ends up on youtube exclusively.
Disclaimer: I work in this field (tech in edu)
Wish them the best though :) Integrate Etherpad for more real time collabo ;) Would be great to have a time slider running along side the video to give more context / detail =)