The video editing software preinstalled on windows 10 is delightfully easy to use! I have pro video editing software but this free version is quite simple to use if doing a simple chore like editing a game video.
Of course, you need video-making software. Or if your streaming app makes a video for you to download onto your hard drive you could edit this. I don’t stream so I am not sure if you would need to convert the video into another file format or not??