Justin Vernon mentioned this Stevie Nicks video in an interview I read recently. He sampled her vocal, straight from the video, for the latest Bon Iver album. He said it's his favorite YouTube video of all time, and I'll be damned if I'm not coming around to that same opinion.
It's Stevie casually singing Wild Heart while having her makeup done for a Rolling Stone cover shoot. I'm guessing the video was shot sometime in August 1981.
She sings like a bird here. Gliding and effortless and free.