Tenspeed and K-girl, we've got (or had, not sure where it's at) a set very similar to the Norpro, heck it could have been for all I know, been so long since I used it. To me, it's too fiddly to mess with, so I usually try to roll the dough wide enough to just fold it over filling. With practice, I've found it's easier and faster to roll the dough out, preferably wide enough to place a ball of filling on, use my finger or a small brush to trace around the filling ball with some water, then fold the dough over to cover, or lay another sheet over the top. I then use a cookie cutter for the size ravioli I want, making half-moons, round, squares, rectangles, triangles, etc. I use a small ice cream scoop that has a lever in it so you just squeeze and it pushes the filling out. They come in just over and under tablespoon sizes and go up.
You just have to be careful, especially when using a second sheet of dough for the top, to make sure and not get too big of an air pocket around the filling ball, again, practice to see the best way to do that for you. For me, it's just gently/lightly folding over the dough (or laying the second sheet down), then pushing individually around the filling balls before flattening out the rest of the dough in between the balls.
With practice you get pretty fast doing it that way instead of fiddling with getting the filling in those little inserts, which also limit the amount of filling and the size of your raviolis.