Backstage after one of her Manchester shows, Billie Eilish holds her hands up to the camera. “Do you see the scrapes?” she asks. The scratches, mild but visible, are from the ravenous audience who pushes toward her night after night — grasping for a hug, a high-five, a brush of her fingers or the hem of her sleeve. And while Eilish professes not to mind (“I come from being that fan, so to me, I understand that need and that desperation”), even her generosity must have its limits. The realities of time and space mean there will always be more people longing to get up close and personal with Eilish than there is of her to go around. Billie Eilish — Hit Me Hard and Soft: The Tour (Live in 3D) The Bottom Line Hits big and small. Release Date: Friday, May 8 Directors: James Cameron, Billie Eilish Rated PG-13, 1 hour 54 minutes Good thing, then, that James Cameron has never been one to limit himself to the realities of time and space.…