I saw the episode, and the remake of it in "Twilight Zone, The Movie". The remake starred John Lithgow, and he did a wondrous job of being the fly-a-phobe that William initially created.

That being the reason that no one takes him seriously...he's afraid to fly, and they think him having a nervous break down.

In the remake, there is one part that was really cool to still frame and single frame advance. John Lithgow was *really* losing it, and they used some special effects to have his eyes pop put...literally. Obviously, a prosthetic thing. The kicker is, though, when it's at full speed, it's a subliminal thing. You just get this weird prickle on the back of your neck, and you *know* this man is terrified. It's a very effective effect.