The math is wrong but not quite in the way you figure it. His point was that if the spaceship launched at the same time as the light left and the spaceship was

The math is wrong but not quite in the way you figure it. His point was that if the spaceship launched at the same time as the light left and the spaceship was traveling at 0.5c. So it would be 1480 years again (1/0.5 * 1480 - 1/1 * 1480).