Yes, they are mating. They stay connected for quite a few minutes. I'm not sure how long after, several days possibly, the female moves the fertilized eggs in a sac to another part of her body where they will stay until they hatch. They don't drop the egg sac, just move it so it will stick pretty far out and then get sucked back in. Sometimes, if the eggs aren't fertile, or if they get too harassed while in the process, or it is not humid enough, and for some other reasons unknown to me, they will drop the egg sac. But once it drops, they don't pick it back up.