Strokes and how to recognise the signs

The NHS has been running a couple of advertisements over the past week or so to highlight recognition signals for when someone is having a stroke. I've never seen a stroke happen, but I have seen the results on a number of occasions and, quite frankly, it can be terrifying, specially when the person involved was well-known to me before as someone who was bright, intelligent and quick-witted. I don't mind saying that having a major stroke, which didn't kill me outright, would be my own special idea of hell. I hope these two advertisements may help someone who witnesses one happening to recognise quickly what is going on and to give the sufferer the best possible chance at prompt medical treatment.

I am intrigued to know how they got the two actors to display such realistic facial traits - I imagine there is some element of image manipulation involved, but it is very clever. And frightening.