For quite sometime, CSGO was considered to be unsuitable for Youtube. Youtube being the largest video network on the web, it was definitely a sore point for many of the content creators. Unable to monetize their content despite having thousands of views was a sore point for many of the youtube channels.
According to this tweet, CSGO videos have been remonetized by Youtube once again. While there is no official confirmation regarding the change, it might just be due to the growing popularity of Youtube Gaming.