Is there a Safari extension which allow the user to select a different folder location whenever there is a new download?
The only way that I know of that allows for selecting a specific folder for each file download is by holding control and clicking the link. A menu appears and select 'Download Linked File As ...'
I was told that you may be able to setup something known as 'Folder Actions' which allows you to create a script for certain file extensions and once the file is downloaded to the default folder the script fires and puts the file in the folder you specified within the script.
I hate this "feature" of Safari, too. But I love Safari's other features enough that I figured out a work-around, until Apple comes to their senses and adds it.
This workflow is designed to ask me where to save a downloaded file, then show me the folder into which it was moved (so I can see the file name) and allow me to change the filename if I want. I need this because several of the sites from which I usually download have long randomly generated file names which are useless, so I need to rename files immediately. If you don't need or want either of those features in your workflow, you can skip adding the second and third actions and just use the Move Finder Items action.
Here's what I do:
Save your file & test.