Most screen recording programs are actually just ffmpeg in the back.

I don't know about well documented, but if you use a standardized argument parser, you can even generate a gui from that.

https://github.com/chriskiehl/Gooey

Well can even make a little Custom Floating HTML Prompt in Keyboard Maestro to push commands to a CLI - just one way

Grsync too

More cryptic commands to the rescue! Lol

alternatively try tldr, which lists the most common options and explains them. It's a livesaver for noobs.

Edit: oh i see it was already recommended lol

While it is an improvement, it's aimed at people that already knows the commands.

For example:

• Extract a (compressed) archive file into the current directory verbosely:
  tar xvf path/to/source.tar[.gz|.bz2|.xz]

What is that [.gz|.bz2|.xz] at the end? to someone that knows the tool it's too obvious to even think about, to anyone else, it's just there to mess with you because there's zero reference to it and some examples include it and others don't.