I've recently become an MOOC enthusiast and have completed some biology courses via Coursera. It seems to me there is an opening for one or more of our more academic minded mudcatters to offer a folklore or traditional Massive Open On-line Course

there are many folky courses on line, mostly not free and very few are in the MOOC format

I've been looking via search engine and come up with some items of interest
If you understand Chinese, check out edX for
02030330X: The Study of Folklore commencing Sep 15th 2014
"This course will concentrate on some of the basic categories of folklore such as myths, folktales, folk festivals, ballads and folksongs. It will be taught in Mandarin."

https://www.canvas.net/courses/ozarks-studies 8 Sept- 7 Nov - includes folklore, folkmusic among the topics of study

Coursera has in the past offered a seven-week long course called "Listening to World Music"/ I don't know when it will be offered again.

no certification:
MIT has archived syllabus, class notes, etc for this on campus course "Introduction to Anglo American Folk Music"; you can follow the syllabus at your own pace and on your own - or set up a study group with other interested folkies