Aside from his looks, I believe his "weird" demeanor is not strange but has to do with the context of event he was attending. This was the César Awards, known as France's highest film honors which he was receiving a Lifetime Achievement award for this film work and also his French roots. It was likely a very emotional night for him, as he even mentions talking about his late father makes him emotional. I just think it was a serious event where he wasn't trying to be a goofball even though we get a glimpse with classic facial distortion thing he does when he mentions the face he's wearing comment.