Developer / Publisher
Aliens: Colonial Marines
Company of Heroes series
Crazy Taxi series
Jet Set Radio
Mario & Sonic at the Olympic Games* series
NiGHTS Into Dreams
Streets of Rage series
Super Monkey Ball series
ToeJam & Earl series
Total War series
Valkyria Chronicles series
Virtua Fighter series
Virtua Tennis series
Details and Conditions
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 firstname.lastname@example.org 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
What it Means
Videos and streams ARE allowed ONLY for the TOTAL WAR series of games
You CANNOT monetize on YouTube and Twitch with ads and subscriptions UNLESS you get direct permission from SEGA per video/stream
You CANNOT sell or charge for access to your content (this would include Twitch "subscriber only" streams)
Any licensed IP or music not owned by the publisher are not covered by this policy
More research is required for other SEGA games