Most people tend to smile in stressful or nervous situations. So it is perfectly understable why the people interviewed were smiling at certain bits of the interview they were giving to NATIONAL NEWS BROADCASTERS.

ITS PART OF HUMAN NATURE OR IS THAT FAKE TOO?

[link to en.wikipedia.org]

Nervous laughter[2] is laughter evoked from an audience's expression of embarrassment, alarm, discomfort or confusion, rather than amusement. Nervous laughter is usually less robust in expression than "a good belly laugh", and may be combined with confused glances or awkward silence on the part of others in the audience. Nervous laughter is considered analogous to a courtesy laugh,[2] which may be rendered by more of a conscious effort in an attempt to move a situation along more quickly, especially when the comedian is pausing for laughter.
Nervous laughter is a physical reaction to stress, tension, confusion, or anxiety - just like sweaty palms or a raised heart-rate. It's not something you consciously choose to do. Nervous laughter has nothing to do with your sense of humor, and can overcome you at the unfunniest of times. Ramachandran states "We have nervous laughter because we want to make ourselves think what horrible thing we encountered isn't really as horrible as it appears, something we want to believe." Those are the most embarrassing times, too, naturally.[3] Psychologist and neuroscientist Robert Provine, from the University of Maryland, studied over 1,200 "laughter episodes" and determined that 80% of laughter isn't a response to an intentional joke

[link to en.wikipedia.org]