A very simple GreaseMonkey/TamperMonkey/ViolentMonkey script to download KWZ files from the Flipnote Archive website. Adds a download button to the bottom of the flipnote.
Simply click on the archiveKWZ.user.js
file, then press the 'Raw' button on top, and you should be prompted to install the script.
Simple, just visit any flipnote on the website, and press the green "Download KWZ" button on the bottom. After that, save the file as a .kwz file.