tmyakal

So Penn & Teller used to do a show called Bullshit where they would investigate things and explain why the “common knowledge” on them was, well, bullshit.

In the episode on handwashing, they took samples from people’s hands, faces, and groins before and after using the bathroom. They came to the conclusion that the before/after on hands was negligible, because most people’s groins are under multiple layers of protection and don’t get exposed to germs.

What they didn’t bring up in the show is that that’s not why you wash your hands when you’re in the bathroom. It doesn’t matter if your asshole is downright sterile, because it’s everything else in the world that is filthy. You wash your hands when you’re in the bathroom because you should be washing your hands regularly throughout the day and it’s easiest to do when you’re already in the room with the soap and running water. It’s got very little to do with anything else you may be doing in the bathroom.

(3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
(4) the effect of the use upon the potential market for or value of the copyrighted work.

Pretty sure these two lines cover most of the examples OP mentioned. Using a sound effect or VO line from a videogame for noncommercial means is both a tiny portion of the totality of the work, and will likely have no effect on the market or value for that work.