I have not listened to her interview because I've read here what she had to say and I am not one to care about how she is presenting herself. I (respectfully!) dislike all the judging about her demeanor, voice, laughing, etc. People are different. Not everyone reacts to things the same. Some people are flighty, some people are very descriptive, some people are negative, etc.; these personality traits don't change in a stressful situation - they are likely exaggerated. I know I use a lot of superlatives and lose my train of thought often... I can't tell a story from start to finish to save my life. I will start into details (that don't even matter) and get off on a tangent and forget what I started off talking about....
That said, I do believe BD and/or the friend are leaving out something that they don't think is important (for whatever reason), which makes them seem less credible.
Edited to add: I keep thinking maybe they just got fed up with his drunk behavior and that is what they are hiding. I know the annoyance of being the sober one and being irritated with someone.