About the plugin
The plugin for SCD is pretty simple. It will add a download button to every song on soundcloud.com!
Why not give it a try? It's free and it will save you from copy/pasting all the links into SCD!
BTW, SCD does not need to be open in the background. By clicking the button, the app will automatically launch and download your song!
Some quick links to get you started:
When using the browser extension with SCD 2.7.0 or above, you have an option which will automatically quit SCD when the download completes. You can read more about this here...