When you see two prominent, A-list actors sign up for a film from a fairly young, up-and-coming filmmaker, it always makes you take notice. What do these folks see that encouraged them to sign up? Is it the story? Well, in the case of Tessa Thompson and Joseph Gordon-Levitt, who both signed up to star in the upcoming film, “Ash,” it’s clearly due to the chance to work with the filmmaker, Steven Ellison, aka Flying Lotus.