What interesting videos.
It is something I knew a little about but not THAT much, the ins and outs of the cheaper dice and the actual manufacturing process.
I've often been tempted to buy casino dice, even cheap, used or rejected ones for that reason, they do tend to be rather large for the average tabletop game though.
Some companies do sell dice with unpainted numbers, basicly that haven't gone through that tumbling process which destroys the edges.
The saddest thing I always seem to run into is that most really nice high quality dice, or dice made of unusual materials (semi precious stones etc) tend to only be sold in standard poly sets. I don't care about those sets, I'd rather have a half dozen d6s or d10s myself.