Firefox: How to not append '.PART' to the file name of the currently downloading file, and just download the file with its normal filename

Question

In Windows, when Firefox (I'm currently using 7.0) downloads a file, it appends .PART to the file name of the currently downloading file and just renames it to its original file name after it finishes downloading.

I sometimes like to watch a currently downloading video file, so it will be better if Firefox just downloads the file to its actual filename (like what Opera does), so I can easily double click the incompletely downloaded file and watch it with the video player assigned to that file extension, rather than the awkward 'Right click -> Open With -> Choose Default Program' route with .part files.

Does anyone know how to set Firefox to do this?

Answer 1

It apparently cannot be done with the stock downloader. Quoting a moderator from the major non-official Mozilla forum:

I think that would require a major rewrite of the downloader of firefox. You can try to replace it with another downloader like FlashGet.

However, a user in that thread reports success using this tightly integrated downloader:

http://code.google.com/p/savefileto/