emfield does support local vids (if the file is uploaded to file server see: http://drupal.org/node/184346 ) & looks like we can develop a custom mod to support screencast.com stored jing vids (we could also download and upload).
I never played with video and need to install on doemo to test. if it is only a cck (and not cck field) then that content can be pushed to a group no problem (study group is a 'group' in our site). only problem is how to associate with 'course', which we could do via a course view etc. actually might make sense its a cck regardless to give teacher flexibility of posting to both organic group and tagging with a tag that a view will add to 'course' view. we should think through how content creators will add what kind of content. i'll write down what i've been thinking as far as what users can do & you can edit or change.
as far as the larger issue of uploading and maintaining files, etc. we should check with harrison b/c I know he's investigating this for his sites. i think we've nailed down how we want to upload or embed images & the wysiwyg editor -- though we still need to get a php-utility imagemagick working on doemo.