

Thinking about sound effects specifically, there are libraries, both paid and free, that you can find online. Those contain a whole bunch of various audio clips. The same general thing applies to graphics, video, and other stuff. That’s usually why you might hear the same effects in different media. Some video game devs might buy the same audio library and you’ll hear the same sound effect in their games. This goes way back to where you would buy CD packs of stock sounds or earlier.
Just doing a quick search online for “sound effects library” took me to https://freesound.org/. I’ve never used it, but it might be good. There’s content all over the internet.
“B-role” would be the term to use if you wanted stock video clips.

That sounds a bit more specific, so it’ll be harder to find. It’s probably out there somewhere. Or maybe you could start one.
When in doubt, there’s probably a YouTube video that’s a compilation of stupid shit a politician said. Download it with yt-dlp and cut it up, lol.