I'm a visual person, so I disagree that porn without plot is meaningless. Why are we playing games at all then, we may as well just read erotic stories and use our imagination then.
virgin has no biological function at all, so it has no value without plot
No one in a porn video / movie is a virgin anyway. At most they can claim that they are in some intro.
straight anal-sex is the same, biologically girls rarely get excited from this kind of behavior, she only get aroused because she believes this is part of the sex, out of love, loyalty, submission, power, degradation or something else
While anal sex will definitely not satisfy most women via its physical sensation alone, plenty of women still find physical enjoyment from it. The anus has many nerve endings. Depending on the anatomy of the woman, anal penetration can stimulate the clitoral legs (clitoral crura). Additionally, depending on the angle of penetration, it can indirectly stimulate the g spot, since the wall between the rectum and the vagina is quite thin.
So with that in mind, body language, facial expressions and dirty talk of an actress can indicate physical enjoyment. Some of those may be real, while others may be fake, but they are acting, so who cares which is which? Just assume that the enjoyment is real, just like you immerse yourself in a written story.
Anyway, you're clearly not a visual person in that case, so I guess we'll just have to agree to disagree on this matter.