Applescript/Automator task to change default downloads folder
Open Automator and create a new service:


Choose: Service receives selected text in Safari like in the screenshot below.


Then add an item Run AppleScript with the content:

on run {input} -- create folder from text

    display dialog " —Create folder from chosen text—
This AppleScript will create  a folder from text you specify."
    set destination to (choose folder with prompt "Where would you like to make the folder?")

    tell application "Safari"
        activate
        if (input exists) then
            set folderName to input
            -- of text of document 
        else
            beep
        end if
    end tell
    tell application "Finder"
        activate
        make folder in destination with properties {name:folderName}
        --select folder "untitled folder" in the destination 
        --set the name of the selection to folderName 
    end tell

    tell application "Safari"
        activate
    end tell

end run

Save the service as Create Folder from Text.


Then in Safari choose some text and right-click it -> Services -> Create Folder from Text.

If the destination folder already contains a folder with the same name the service fails without any further notice.



If you don't like the dialog "—Create folder from ..." add a # in front of it or remove the two lines.



If you replace:

        tell application "Safari"
            activate
        end tell


by

        tell application "Safari"
            activate
            set destination to (choose folder with prompt "Where would you like to save the new file(s)?")
        end tell


the Automator service will open the new folder and ask you to choose the new folder as new download folder. Simply hit Choose. If you then right-click the download link -> Download linked file as…, the file will be downloaded to the new folder.

The script may be improved further, because I didn't get it to work to set the new folder as new download destination automatically.