Not only that, but all the friends' testimony in this area suggests that it was Meredith who was getting annoyed with Knox, and not the other way round. In fact, this testimony only tends to support the notion that Knox was a laissez-faire type of individual, who might not have been appropriately aware of the impact of her behaviour on others. It certainly doesn't suggest that Knox was the type of person who might fly off into a rage - let alone one that would end in a vicious murder. It seems not many pro-guilt commentators have paused to consider this aspect very much. All they seemingly see is this: any criticism of Knox = grist to the mill of her culpability in Meredith's murder.
In addition to the above, Natalie Hayward had known Meredith for all of two months by the time of the murder, and would hardly have known Knox at all. By the sounds of this interview, it appears that Hayward barely even met Knox. And saying "she was actually there" is only true up to a very general point: she was a fellow student in Perugia, and she knew Meredith Kercher. But she couldn't have been privy to any deeper dynamic of the relationship between Knox and Meredith. She wasn't at the girls' house where Meredith went to watch the DVD and eat pizza on the evening of her murder. And she wasn't "there" on the day after the murder when the body was discovered.
Apart from all that, pretty much everything said by Hayward in this interview (the "weird behaviour" of Knox at the police station, Knox's supposed knowledge of details of the murder, her views on the Knox "accusation" of Lumumba, and so on) can be viewed as post-facto rationalisations. What would have been extremely interesting to know, for example, is what someone like Hayward might have been thinking abd saying contemporaneously: what, for example, did she tell her family in the UK in phone calls or emails, or even after she arrived home from Perugia (seemingly before Knox was arrested)? If I were a betting man, I'd be willing to place a large bet on her not having had these suspicions of Knox at that time. I think that she has - perhaps understandably - bought into the idea of Knox's guilt, and has then gone back and rationalised everything to fit in with that belief.