Some people attribute his eccentric behavior to post-traumatic stress syndrome from his service as a pilot in Vietnam.
8 seconds sound clip from the Independence Day (1996) movie soundboard.
You can hear this line at 00:34:31 in the Blu-ray version of the movie.
Quote context
[...]
- Can you give us some of your time? Do you want to make a statement?
- I was kidnapped by space aliens ten years ago! They did all kinds of experiments on me!
- They've been studying us for years, finding out our weaknesses!
- We've gotta stop them! They're gonna kill us all!
- Others, however, have a more unusual theory.
- How would you describe Mr. Casse?
- Private.
- Quiet.
- When they took him up in the spaceship, the aliens abused him sexually.
[...]