The IELTS interview gives you roughly 10 to 15 minutes of time to display your English speaking skills to the examiner. If you give one-word or very short answers to questions you are not giving the examiner much with which to assess you.
Even if you are asked what seems like a yes–no question you are expected to say more than a simple “yes" or “no”. You should try to develop what you say by, for example, giving reasons, opinions or describing something in more detail.
In the video clip Joao is asked to tell the examiner something he likes about his job. He answers by saying “the people”, which shows that he has understood the question, but it doesn’t show off any of his English skills. What he needs to do, which eventually he does with some prompting from the examiner, is to develop his answer and describe in more detail why he likes the people he works with.
A good tip for candidates is to look for signals from the examiner. Often you can see from the examiner’s facial expression or manner if you have said enough or not.
Examiner: Can you tell me something you like about your job?
Candidate: The people. People are nice. They are positive. They are…