Thanks for making this video, @robcubbon!
I will def take a look at StackSocial and StackSkills. Also the other ones you mentioned.
What I find a bit frustrating as a video course producer is that a lot of the course platforms out there focus specifically on digital skills (Coding, Wordpress, Design, etc). I don't teach that.
I have a course on 'yoga for beginners' and one on 'boosting focus and productivity'. Especially the first one took quite a lot of time to produce, much more intensive than simply making a screencast video course. Yet there don't seem to be many platforms where I can publish them, and thus recoup my investment.
You didn't mention Skillshare, and I guess with good reason: A year ago revenue was promising there, and I spent a good amount of time to learn about the platform and chop up my courses into shorter 10-25 min classes, which is what Skillshare prefers. But when they changed their algorithm around October 2016, I walked away. All the work I had put in ranking for the keyword 'Productivity' was undone when all of a sudden totally unrelated courses with lots of students on 'Producing Music' and 'Selling Products' also showed up for the 'Productivity' keyword. Ridiculous.
TOTALLY (caps lock OFF!) agree with you about Skillshare. Just giving up on that platform. Really bad UI and, yes, at one point they wanted short courses and then they wanted long courses. Won't even bother uploading there again.