Fanning powder is pretty useful if you like learning card flourishes. It makes the cards easier to work, and helps keep decks in service longer.
Fanning powder is mostly zinc soap (zinc stearate) and some other magic filler. It fills the gaps, cracks, scratches and other imperfections that develop on playing cards as one obsessively shuffles, reshuffles, cuts, and manipulates them.
Applying it doesn't have to be this hard, but the dude in the video makes it look cool! I prefer not to get powder all over my home, however. I place one teaspoon of the powder in an arcane device known as 'a plastic bag' and shake the cards around in it. Much like fake the fake fried chicken of our youth.
A few riffles through the reorganized deck cleans them off. Do not bake.