Firefox testing addon that shows archived pages instead of 404's

Recently the Internet Archive and Mozilla announced “No More 404s”, an experiment to help you to see archived versions of dead web pages in your Firefox browser. Using the “No More 404s” Firefox add-on you are given the option to retrieve archived versions of web pages from the Internet Archive’s 20-year store of more than 490 billion web captures available via the Wayback Machine.

Here's a guide on how to set it up in combination with the wayback machine.
https://blog.archive.org/2016/08/09/no-more-404s-resurrect-dead-web-pages-with-our-new-firefox-add-on/

Want to help out archiving the internet? Have a look at archiveteam.org and join URLTeam!