Add-ons can be distributed outside of AMO. A secondary (more scary) dialog is shown before the add-on can be installed, but users can click past it to get to th

Add-ons can be distributed outside of AMO. A secondary (more scary) dialog is shown before the add-on can be installed, but users can click past it to get to the add-on. PDF.js uses this approach actually. See "Development version" at https://github.com/mozilla/pdf.js/ https://github.com/mozilla/pdf.js/ as an example.