

i think this is the correct question to ask. did you just create ~/.local/bin
folder? you can look at the end of ~/.profile
that this will only be added to $PATH
if the folder exists.
the easiest way is to log out and log in (no restart necessary!)
otherwise you can also execute source ~/.profile
and then yt-dlp
should be available.
the chmod +x
tip from the other comments could also be necessary!
how do you buy stuff online? do you read reviews on the big shopping platforms?
back in the day reviews were a good and honest way to find out if a product is usable. the idea was that normal people do honest reviews and other people can use that as a guidance.
this was probably true for some years, until the system got rigged: users were payed to take bad reviews offline, or users are payed to post good reviews. simple products with good reviews got exchanged with cheap complex products, so the reviews seemed to be for that product.
what you see is one part of this system: a seller is asking you to do free advertisement for them.