Why is she nervous? This is just an interpretation. This role is for men who can no longer fuck their pussy, they no longer have an erection and have become lazy. It seems to have an effect on those watching. Regarding this scene, it seems that the man doesn't know how to put tongues in the pussy well and that makes the scene almost real.
This is definitely one of the best videos I've ever seen. Although the video quality is not so good, but the woman is professional. The way she squeezes the guy's head between her thighs while he sucks on her pussy is amazing! Domineering women like that are the best!