This act makes it illegal to download a video and share it.
It is however legal to share a YouTube video, as long as the creator gets the credit. For example, using the YouTube share feature.
You must have a license to stream video games.
Without a license, streamers do not have legal rights to uplaod streams of a compyrighted protected video game.
You can use audio from a service you pay for, or a legal service that offers it for free. For example, YouTube, Spotify..
If you have physically brought the audio, you can copy it for personal use, fully legally.