When I first saw that video the following comment was below the video.
Pro-Tip:
Do not,
DO NOT,
*D*O* *N*O*T*
Shoot Dragon's Breath magnesium incendiary rounds indoors.
I found another angle fired. Doesn't look like dragon's breath, but looks like more flash than I'm used to seeing from LTL rounds (fire starts at 1:25)
My thoughts:
1) Poor range maintenance.
2) Poor range material (wood floor, non-FR foam on walls)
3) It's Brazil Federal/Military Police, so I'm guessing that OSHA/NIOSH isn't really a thing there.
"If you think it's expensive to hire a professional to do the job, wait until you hire an amateur."
Disclaimer: I have previously worked in the firearms industry as an engineer. Thoughts and opinions expressed here are mine alone and not those of my prior employers.