An error occurred while saving the commentMastahiro commented
Game music/assets/video/footage are no different to other music as stated by other users.
Some companies have a clear policy when it comes to streaming or making videos with their assets such as Blizzard (https://www.blizzard.com/en-us/legal/dd76b654-f2c4-4aaa-ba49-ca3122de2376/blizzard-video-policy) while others don't and can take legal action at a moment's notice if they so wish to.
It falls upon the streamer to check if they can legally stream said game/music or not.
Some years ago, Nintendo did try to enforce people join their Creators Program to make videos (https://en-americas-support.nintendo.com/app/answers/detail/a_id/14034/~/nintendo-creators-program---overview), where the creator got a percentage of the Ad rev. They eventually took a step back as people simply stopped promoting their games. Current Nintendo guidelines: https://www.nintendo.co.jp/networkservice_guideline/en/index.html?n
Try looking up "<game> streaming policy" and if you don't find it, it's a risk you're taking.