Apple - How do I install handbrake cli?

The best way to install anything on OSX is (IMHO) with Homebrew. You can install Homebrew with this command:

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Then you can install stuff (like handbrakeCLI) like this:

brew install handbrake

Then you can run it straight away from any command prompt with:

handbrakeCLI ...

/usr/local/bin is meant for installing local (UNIX) software. Conveniently, it is also included in $PATH by default, so you don't need to prefix the full path to run commands installed there.

You do need root access to install/copy files there, you could accomplish this by using sudo while moving the binary there.