Many firearms and, especially, black powder forums prohibit the posting of receipes for making black powder because of the great inherent danger in the process.
I am an avid muzzle loader using black powder only. I would never attempt to make it except in an extreme survival situation.
I did not view your video and do not intend to.
I understand your concern, Rifleman, but when you talk about danger, there is great inherent danger to anything and any hobby that is out there. You should see what the rat-rod builders do on motorcycle forums. They share information about how to build the biggest and most horsepowerful beasts and some of them have little or no background in mechanics.
Is it dangerous to operate a hobbyist-built custom motorcycle that could puts out 450-HP and reach 0-60 in 3 seconds? Of course it is but if the job is done by responsible, professional people, the danger element is about eliminated.
What about kitchen-table gunsmithing? I have been a machinist for a long time and I have seen what disasters could happen when you give a Dremel tool to someone who doesnt know how to use it, or too enthusiastic.
Is it dangerous to make black powder? Of course it is, but a responsible individual does it with proper equipment, such as a well-inspected mill drum and non-sparking grinding medium, like golf balls that I use.
Almost everything is common sense and when that is used, everything is very safe.