Ah ha! Figured it out, you just need to have a status ailment, from the 2nd hydra's poison spit, or the archydra's blinding poison spit, then it'll gulp you up without a QTE.
Anywho, I suppose I should end my updates here, don't wanna spam the board or anything. ^_^;
I hope this' been informative for those who buy the game, or borrow it from a friend, whatevs. Vore aside, it's a GREAT action/adventure game. I've only really played through the game as one of the 9 vocations, and I'm eager to try out the others sometime! =D