At its core, the phrase appears to suggest that a rider, presumably of a vehicle or a horse, doesn't require pants to navigate or enjoy their journey. On the surface, this seems absurd, as pants are a fundamental article of clothing that provide protection, comfort, and modesty.
While the file itself might be lost or simply a placeholder for a prank, "A Rider Needs No Pants.avi.rarl" is significant for a few reasons: A Rider Needs No Pants.avi.rarl