An "iso shot" in TV or movies is the feed from a camera acting independently from the main array, whether it's one or four or whatever. "Iso" is short for "isolated." For instance, a director on a TV show shot with three cameras might also have a fourth camera called an "iso" that is there to grab random shots outside of the main plan. Or a director on a movie with one camera might have a second camera around to grab a shot of something from a different angle. It's kind of like a bonus camera.