The Okay Man
I want to use YGOPro for videos in YouTube. I want to show a bunch of duels with music over the top (royalty free). I was told that I am not allowed to do this due to copyright.
"Gameplay content that incorporates commentary over the entire duration of the video, step-by-step commentary that is strictly tied to the live action being shown, and muted in-game audio reduces your risk of liability for copyright infringement."

Bee Ba
If you choose to play music through the entire video, you're not held liable. It only matters if you are trying to monetize your video. Even in that case, all that happens is that the companies/artists will get the money from your videos instead of you if you're using their material. Youtube automatically does this. Unless you have more than >2000 subscribers, monetizing will just give you enough to buy a single beer a week.