but is not for free and its not necessary to spend one ‘cent’ into video recording for youtube. I know all these videos/sites which compare video-quality ( e.g. the diff CPU vs nvenc , some tools, and on.. ) and then, at the end, come Youtube with its own algortihm and all the high-quality stuff is gone 
Beside of shadowplay , I also use OBS ( also for free ) in cases where e.g. I need more detailed seperation of audio tracks, etc.. But its not so easy to use as shadowplay and depend on game it have an effect on performance.
ah, can be in meanwhile .. I not care about much , because most youtubers not aware of the difference. So is for me not worth for yt ( only in case you like these clickbait videos descriptions like "a real pilot reacts in 4k hdr ultra settings you not believe how bla bla " 
)..
PS: I do a little bit overstate
its a big topic as @Neo4316 mentioned too. The music in a game is of course recorded as well, but some of it a copyrighted and thus you get a “message” from youtube with a choice ( e.g. yt try to remove the music or added advertising in case the music ower allow that ). I allways try to never post copyrighted music because my goal is “no ads in my videos” → it makes no different for me, but for the people which watch at the end my videos ( I know, on bigger channels yt add ads without asking you ).
In general its also like Nes4316 have mentioned, I don’t like music in videos. In special in videos about a flight-simulator is music for me a immersion breaker ( I not mean trailers or so )..
If you want go future steps with video editing, the best FREE video editing software I can recommend is davinci resolve. You can buy a extended version too, but most of the features in that studio version are made for professionals ( e.g. share work on different machines ) and not necessary.