Outside of video "documentation," little is known about the rare phenomenon:
It wasn’t until 1982, in fact, that female ejaculate was first chemically analyzed. If it’s not urine, and it’s not semen, then what, exactly, is it? After all, according to an interview study (pdf) published by Amy Gilliland of the University of Wisconsin, Madison, most female ejaculators report "copious" amounts of fluid being released around the time of orgasm, enough to "soak the bed" or "spray the wall" or have their partner scream in terror and misunderstanding. So it’s rather odd that we still don’t have a name for this substance that 40 percent of women report having produced liberally at least once in their lives. … "No research has been done in this area for over 20 years," laments Gilliland, "and we still do not have an answer satisfying to most sexologists as to what female ejaculate fluid is or where it is manufactured."
The Dish 