So I was watching a Brian Greene doc on Youtube about Time and he says motion through space effects the passage of time. see video at 15 minutes til 17 minutes - can't link the video but its called The Illusion of Time.
I understand how distance between observers and gravity effects time but not motion. So If im sitting opposite a person and they walk 20 feet to their left but are still the same distance to me then why would that effect the time of my observation?