At 5:52, I'm pretty sure he said "a blue disc". When he flips it over, you don't see through it, it's pretty much opaque.
I stopped by the Fisherman's Warehouse today, to pick up a few colors of Spike It worm dye to try with some spin dyes. I didn't count, but it seemed like they had about 12 colors. Most interestingly, one which was white! Perhaps this is how he is getting a lighter color than the original material. I too am skeptical of achieving that kind of result without adding a base material or paint.
Next time I go by FW, I will count how many colors they have, and may pick up the white to try out.
On the same topic, has anyone tried bleach to lighten the color of the plastic before dyeing?
BTW, I am very thankful for this thread, and hope to contribute to it soon. I have been experimenting with some So-Strong colorant that I use with plastic casting for another hobby of mine with OK results on some quick tests.
Peace,
-Jeff