Yes. IMO, GBC's sister displayed nervousness and uncertainty.
As a psychologist, I do tend to closely observe body language, even when I'm having a casual conversation with a friend (I know, my poor friends, family etc!). However, there are a couple of things I'd like to say about this: Firstly, IMO, most people don't need a "piece of paper" from a university to prove that they can read another's body language - this is typically a trait that humans develop through their formative years, with some people being better at it than others (and, without wanting to sound stereotypical, it has been acknowledged that women are better than men at this!). So, for many of us looking at media photos/videos, we immediately get a "feel" for whether or not a person is being honest with us. The amount of information that is presented through non-verbal means makes up approximately 90% of our communication.
Secondly, I'd like to point out that we are only getting small snippets in time, of images of different members of the BC family. The problem with this is that there is always the possibility that the media is trying to sway public perception one way or another. So, if they want us "believe" that someone is guilty, the photos or videos that are published will promote that line of thought. MOO.
In saying the above, I still believe that GBC's one and only media interview speaks volumes. And, unfortunately for him, the image that he has projected in this video is very negative. MOO.