SEGA

The only statement I found was in regards to the Total War series:

"As an individual, you are allowed to record and upload footage of our games for not-for-profit / non-commercial purposes that are not aligned to a political, religious or charity movement on a freely and publically-available media or service (eg. Youtube)."

"Please mention either in the video itself or in the notes or comments accompanying it that it is not an official video and that anyone interested can visit www.totalwar.com for more information on the game."

"Please note that if you do monetize your channel you will need to remove any Total War footage unless you have arranged a permission agreement with us. If you wish to do so please contact licensing@creative-assembly.com and we will introduce you to our commercial licensing department at SEGA who can help provide this."

In short, SEGA officially only permits YouTube monetization for just one series of games, Total War, on a case-by-case basis that requires contacting their licensing department for approval. You can try to contact SEGA in regards to other games but based on the wording of this one article, it doesn't sound like they are open to allowing monetization using their games.

See more details by clicking the "source" link below.

*uses licenced characters or IP not owned by SEGA and may require additional permissions from those respective rights holders