NOTE: Support for MP4 Downloader has been discontinued.
I don't have the time anymore to keep up with all the changes that YouTube, Dailymotion, and Vimeo make that affect video downloading, along with keeping up with the latest changes in Firefox.
The codebase has been left in the middle of a complete rewrite (see the Source Code section of the Development page). That codebase, and this website, are left here for archival purposes.
Want to contribute to the documentation? See the Website Source Code section on the development page.
Here is a list of some of the terminology used throughout MP4 Downloader and its documentation/wiki pages.
For more information for developers, see the development page.