Part 5/15:
The Flat Earth advocate, Wit It, counters by claiming that star movement is due to perspective, due to some kind of star rotation or a moving starfield, or that the north star's position changes over millennia. Dave counters by pointing out that the observed rotation directions are consistent with a rotating sphere, and that such behaviors are explainable only with a spherical Earth model with stars at varying distances and angles of rotation.
Key Point: The star trail rotation direction provides a straightforward, observable proof of Earth's spherical nature, which Flat Earth models cannot provide without resorting to complex and unsupported explanations.