Got Docker? To help archive the amazing CC-licensed art on 500px before they try to enclose that commons tomorrow, do the following:
sudo docker pull archiveteam/warrior-dockerfile
sudo docker run -p 8001:8001 archiveteam/warrior-dockerfile
Visit in your browser: localhost:8001
Setup a username.
Click "Available Projects", select the 500px project.
Check it's running at "Current Project"
..that's it. You're helping save the Commons. You don't need to do anything else.