Recently I have heard many students complain about their stress levels going up because of IELTS and their upcoming test date. Unfortunately, there is a direct link between stress and the ability to remember information including the things I teach my students in IELTS class. Therefore I try to help my students control their stress and I always tell them to take time out to eat well, exercise and relax so they can do better on their exams. There is no point studying for many hours per day if your brain is too stressed to remember what you are studying.
Take a look at these TED videos about stress and how it impacts on your learning and memory.
No it is not a waste of time to watch them. Think of it as listening practice for IELTS.