Duck for the Oyster / Grapevine Twist
Filmed in Super-8 by Bob Dalsemer, May, 1979, at the Vandalia Gathering, an annual festival in Charleston, WV, sponsored by the West Virginia Department of Culture and History.
These dancers are from Glenville, WV, which now hosts the annual West Virginia Folk Festival, which begins the 3rd Thursday in June each year. There's dancing each year on a specially designed wooden platform erected for the occasion.
A search for "Grapevine Twist" in this project's digital collection will return at least four other video clips showing that figure, including Elizabeth Burchenal's silent footage from the 1930s.