You do know that most of them not to say all of them, but must are just peeing. Those big gushers Is just pee, look at it it's to clear. Has to be pee.
I know from personal experience big gushers aren't peeing. Nor are littler squirters.
About sites and movies that have actresses who gush big, probably they drink a lot of water first, it may add to the effect, though I don't know if there's proof of this. It takes time for ingested fluids to reach bladder and internal glands. But squirting is rarely if ever peeing.
"The expelled or released fluid is not urine, it is an alkaline liquid secreted by the paraurethral (alongside the urethra) glands."
See Wikipedia and its references: http://en.wikipedia.org/wiki/Female_ejaculation
I know performers who are chronic squirters. They love it and try to do it whenever they can lol ... I'm exagerating, but they just seem to have a bottomless reserve.
I wonder though if this one chick couldn't come herself to dehydration though, quite copious.