Support for MP4 Downloader has been discontinued.
I don't have the time anymore to keep up with all the breaking changes that Mozilla is making in add-on development for Firefox, in addition to reacting to changes in YouTube, Dailymotion, and Vimeo that affect video downloading. Since Mozilla dropped support for traditional add-ons in November 2017, MP4 Downloader has stopped working entirely in new versions of Firefox.
The codebase has been left in the middle of a complete rewrite (see the Source Code section of the Development page), although this rewrite is not anywhere close to what is required to support new versions of Firefox. That codebase, and this website, are left here for archival purposes.
To all MP4 Downloader fans, thanks for many years of support.
Click here to download version 1.3.3 (the latest stable release).
You can also download MP4 Downloader from the Mozilla Add-ons site.
This is the older branch for old versions of Firefox. This branch is still maintained with some updates, but new features will not be added. To download the latest version in this branch (version 1.2.15), click here.
To view the MP4 Downloader changelog, click here.
If you are interested in trying a beta version of MP4 Downloader, see the development page.