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.
If you have any issues or questions with MP4 Downloader, send an email to: mp4downloader -AT- gmail -DOT- com
If you are reporting a bug, it might be helpful to glance over this page first: http://www.chiark.greenend.org.uk/~sgtatham/bugs.html