"I just saw that guy throw a ball."
"[T]hat guy," the direct object, is now doing the action of "throw[ing]." So, could one ask, "Whom did you see throw the ball?" or should it be "Who did you see throw the ball?"
I would naturally replace "that guy" with "him" if I wished to say it that way, so--assuming that is correct--does that mean "that guy" is always treated as the object despite doing an action?
Sorry if my phrasing is confusing; thank you for any responses.
Edit: This has been marked as a duplicate, but the linked question does not answer mine.