Use Bandicam (the free version is enough), with an option to record mic and sound on one or two audio tracks (two is best so that if the sound of the game drowns out your voice, you are able to turn the game sound down). The low quality of the video is most likely due to the compression you have used (or lack there of). In Windows Movie make (for example) it gives you the option of the quality of the .mp4 file you wish to upload (this being your video). Preferably do not upload .avi files to YouTube, as in my experience the upload quality is set to the minimum. I hope this helps.