Royal Nonesuch posted that Youtube started to demonetize his video due to South Korean government banning his videos.
In October, a Korean killed a responding officer with a homemade gun. Korean laws were strengthened earlier this year and any information that shows how to build a firearm are getting banned. The incident only accelerated the move.
What is unsettling is that Youtube is penalizing videos that are perfectly legal in US. Instead of blocking the video from a region, which Youtube seems to be capable of. They are penalizing certain contents, which won't have a big backlash as outright banning it.
Additionally, Mark Serbu (of Serbu Firearms) is getting similar treatment.