here is another site that has a picture of "slingshot yak herding" about half way down.


www.bikechina.com/ct-dw-lhasa-everest4.html

he appears to be using a longish sling, with the 45 degree overhand or underhand syle.  interesting that these herding types have good accuracy with longer slings, when we seem to have better accuracy with short slings.  oh well, i suppose if you have never felt a short sling, you would develop accuracy with the longer sling.


EDIT:
here is a pretty dramatic pic of a person slinging overhead with  a most likely sidearm release

lawrenceofcyberia.blogs.com/.../slingshot.html

edit again:
a couple of boys weilding slings
www.bobmay.info/dec042002curfew.htm

edit yet again:
a boy uses a sling that seems to made from torn bits of a t shirt
www.cnn.com/.../gallery.basra/content.1.1.html