Thanks, @danbp! It looks as if BuddyDrive would meet some of the basic requirements. I’m starting to think that I may have to give up on turning individual content items into posts, so if that happens I’ll certainly be looking at BuddyDrive.
By the way, I should have specified; my plan here is to have each and every media item be its own post. My thought process is that many organizations won’t want the whole collection, but I don’t want then to have to search for each part of a collection one by one.
For example, if someone searches for “Christmas” on the content portion of the site, I want them to see results that lead with entire media collections, but can be sorted by media type (video, study guides, etc) via search result categories off to the side.
I’m thinking that the post type for entire collections would simply contain a hero image and description, with all of the related post types (individual media item posts) thumbnailed and listed below.