 In this one clip alone, I would have said there's something off about the entire case. You can see her pacifying a lot, which is almost always what people do during stressful situations. However, at the same time, she's not exhibiting many more signals of stress, and she's doing quite the opposite of stress. She's demonstrating stress and self-soothing behavior while trying to build rapport. That's the mistake. She's trying to build rapport with the interviewer here. This behavior alone is so incredibly common in guilty people that I might say that it would be on my top five list of things to look for. If I can get them to like me, they're more likely to believe me when the questions get a little bit harder when it's time for the story to come out.