How does one pronounce the ɧ sound?
Like in Sjunger or skjorta.
I found that video very helpful and am glad you posted it for others to see. There's one that is a radio show doing Swedish tongue twisters which I found useful too. Not so much for educational value as such; but, as a good example of the sounds used at full speed in ridiculous situations. I want to be able to do the 7 nurses tongue twister quickly one day! hehe
Another I just found that you might enjoy is from a beautiful young woman talking about some of the ridiculousness of her native language. Your comment about hissing is echoed in her comment that her cat gave her funny looks when she made the video with these sounds.
It is worth noting that pronuntiation of sj-ljudet differs largely in Sweden. Difference in pronuntiation can depend on region, gender, situation, whether the sound is at the beginning or the end of the word and so on. You can find some information on this in wikipedia
I already knew these great videos but I didn't imagine at all that Academia Cervena was a Duolingo moderator! :-)