Hello, I saw the video, I loved the expression on that guy's face when he saw the needler!! What I usually do to get rid of the white lines (which especially stand out on cardstock) is to use water color markers to color them in after I cut the pieces out. I do this even before I score/fold the pieces. After much browsing, the best product for its price to do this is crayola pipsqueak markers.
Smallest tip, multiple colors so I can find the right color to roughly match the ink, and doesn't have to be massive markers since i'm using these only to color edges of paper, not bad for its price. Tricky to use at first cus you have to color the edges in one smooth swoop or else it'll bleed into the paper too much. Also, I would try to pick a color that I think will match the ink, and color the edge of a glue tab and put it on top of the thing i'm trying to match to see if the color is good, and keep trying until i'm satisfied before coloring the edge of the actual piece. Once you get the hang of it, the final product is awesome. I habitually do this for every single piece for all of my models.