Stress in cadet interviews
Unfortunately I have to concur with 404 when he says that lack of preparation was the key. People often study their butts off because they anticipate questions that will be of high technical standard. This is true and I cannot emphasize enough the importance of technical knowledge in a CX pilot interview. However what people don't always realize is that mental/psychological preparation is equally important, simply because being a pilot requires a certain degree of ability to deal with stress and pressure. Clearly if you go in expecting a pilot interview to be relaxed and friendly, that is a good indication that your understanding of the line of work is lacking. You don't always get smooth sailing for every flight and almost every day you turn up at work, something will be different and it will be up to you to deal with it as it comes, all the while keeping the entire operation safe and efficient. You cannot be a good airline pilot without being able to deal with this type of stress, which is why the interviewers deliberately put pressure on candidates. They want to find out if someone will crack.
I don't think it is any particular thing that chaz88z said that caused him to fail. I would simply say he was not prepared well enough psychologically, which probably showed in the way he dealt with the interview.