However, I'm not saying that their licence should be taken away (we've all made mistakes - I should have made that clear), but if that is representative, it is dangerous. I rode motorbikes for many years, and you can spot people who are dangerous very quickly from their 'car body language'. And an error like that in another circumstance could kill someone.
I knew people whose driving had deteriorated like this (my late mother and her friends spring to mind). They refused to accept they were not capable any more, and she used to do things that terrified me. I had discussions (kindly!) about her driving standards and errors and she refused to accept that she was making the errors she was. And they were not as bad as what I saw in the video.