I watched that segment. Interesting things I noticed:
1. Letterman repeatedly attacked O'Reilly while simultaneously admitting that he didn't know anything about the issues.
2. I'm going to add a description of Letterman's demeanor during this exchange:
Letterman: See, I'm very concerned about people like yourself who don't have nothing but endless sympathy for a woman like Cindy Sheehan. Honest to Christ.
[audience applause]
O'Reilly: No, I'm sorry.
Letterman: Honest to Christ.
O'Reilly: No way. [waits for applause to die down] No way you're going to get me, no way that a terrorist who blows up women and children.
Letterman: Do you have children?
O'Reilly: Yes I do. I have a son the same age as yours. No way a terrorist who blows up women and children is going to be called a freedom fighter on my program.
[mild audience applause]
(Notice Letterman has no response to this)
Letterman (Somewhat anxious) : I'm not smart enough to debate you point to point on this, but I have the feeling, I have the feeling about 60 percent of what you say is crap. [audience laughter] But I don't know that for a fact.
[more audience applause]
Paul Shafer: Sixty percent.
Letterman: Sixty percent. I'm just spit-balling here.
O'Reilly: Listen, I respect your opinion. You should respect mine.
Letterman (Sheepishly) : Well, ah, I, okay. But I think you're-
O'Reilly: Our analysis is based on the best evidence we can get.
Letterman: Yeah, but I think there's something, this fair and balanced. I'm not sure that it's, I don't think that you represent an objective viewpoint.
O'Reilly: Well, you're going to have to give me an example if you're going to make those claims.
Letterman (Sheepishly): Well I don't watch your show so that would be impossible.
O'Reilly: Then why would you come to that conclusion if you don't watch the program?
Letterman(Sheepish, uncomfortable): Because of things that I've read, things that I know.
O'Reilly: Oh come on, you're going to take things that you've read. You know what they say about you? (Letterman actually looks embarrassed at this) Come on. Watch it for a couple, look, watch it for a half hour. You'll get addicted. You'll be a Factor fan, we'll send you a hat.
3. Letterman proves that he is NO journalist, but an entertainer, and an ignorant, embarrassing one at that, zig-zagging all over the place without any facts. (Exactly like you Fiberals.)
4. O'Reilly proves that he is a journalist, with answers to every attack and even a sense of humor, while he sticks to his principles.
5. Letterman came off as an ignorant jerk, while O'Reilly came off as a disrespected guest who gave a good account of himself.
End of Story.