when downloading lots of videos, you will have to take some compromises for it to be economical. like you probably dont need full quality, especially when its 4k or something insane like that. so you will want to use a very simple parameter like this:

-f "bestvideo[height<=?720]+bestaudio/best"

already memorized it, right?

or, what if you would accidentally redownload a video? you forgot you already downloaded a specific video, so you rerun it. maybe even its content has changed since then. or you are downloading a playlist or a whole channel, and you dont want to redownload existing ones all the time. what you do?

--no-overwrites
--archive-file filename
--force-write-archive

or if you dont want to download formats that might be a pain in the ass to play later:

--prefer-free-formats

but yeah, you can ignore all of this and be surprised later when you can’t sustain your archive anymore. or use a gui tool that shows these settings in a prominent place so you can decide in time.

oh and don’t forget links that your terminal could misinterpret as a standalone command to run, because it has an ampersand or something like in it. the average user is not experienced with the terminal to quote every URL