The Natural Extension Concept (often abbreviated to the N.E.C.) deliver droning, druggy, psychedelic behemoths that come swathed in feedback and throbbing rhythms. “Sally,” a highlight off the Atlanta band’s upcoming R U GOING TO THE SHOW? LP, is no different, and neither is its music video. The three-and-a-half-minute clip conveys everything newcomers need to know about the trio without conveying much of anything at all. It’s a wash of LSD colors and faint stock footage, big city skyline, a woman swiveling her hips, and someone running panicked past the camera. Wade into the mess above.