As I understand it, female ejaculate actually comes from the Skene’s glands. Though since we’re talking about porn production, I hasten to point out that a balloon or hose positioned within the vagina would not look appreciably different to a layman, absent an extreme close-up view (a view that would be immediately obscured by the liquid upon the camera lens).
Powers &8^]
I’d recommend Slavoj Zizek on the matter too, he’s somewhat of the opinion that pornography has to be an idealised (explicitly unrealistic at any rate) fantasy matter in order for the whole affair to occur. I’m not sure what the mechanism behind that function would be, but I haven’t seen any evidence to the contrary (involved, emotional, perhaps flawed intercourse). Unless one counts pornographic novels, though Zizek argues that males tend towards voyeurism and women more towards narrative.
Chomsky also comments that consent, even informed consent, can be given in quite shady circumstances in other instances: he compared it to working in a sweatshop.
In at least some women studied, it isn’t urine. It’s very clearly chemically different. That doesn’t preclude the idea that some other women do have urinary stress incontinence at orgasm.
Science seems to take a very stupid approach to female sexual function, however. Rather than being able to grasp that there seems to be some natural variation (some women can’t orgasm, some only with difficulty, some are multiorgasmic, some report erotic sensation in their vaginas, some are only able to find sexual pleasure in intense clitoral stimulation, some orgasm from nipple stimulation), the approach tends towards “Well, the women in this small group are like this, so all women must be like this.”