Q: Can masturbation really "speed up" a period?
I'm honestly not sure. On the one hand, orgasms do stimulate uterine contractions (and masturbating before or during your period can therefore stimulate cramps), so it seems like it would work great. On the other hand, I've noticed that menstrual flow can decrease greatly (or even stop completely) during sexual arousal, so that might counteract the effect of the cramps/contractions.
All in all, masturbation is fun and certainly isn't going to hurt anything, so I'd say it's worth giving it a try!