Stable AMO Version, see changelog for details.
You can get latest stable version here, too, using this
direct download link for FlashGot
To install, just drag and drop it onto your address bar.
If you find any problem installing it, this FAQ may help.
If you're brave enough and you need a specific fix not released yet, or you simply
want to provide feedback before official release, you may try this
v 18.104.22.168rc1 ===================================================== + E10s-compatible API + Video DownloadHelper integration x Restored Nightly compatibility broken by bug 1253016
You can also discuss about FlashGot on this Forum.