There's a regressive Bug in Firefox 32 beta 9 which is related to Downloads completion.

There is unfortunately a regression bug in the current Firefox 32 beta 9.

You can create a new String pref on the about:config page via the right-click context menu. Name: browser.safebrowsing.appRepURL Value: https://sb-ssl.google.com/safebrowsing/clientreport/download?key=%GOOGLE_API_KEY%

Bug 1057764 - Download Manager regression in FF32 beta 9 update Please do not comment in bug reports
https://bugzilla.mozilla.org/page.cgi?id=etiquette.html

mugilash said

when ever i try to download torrent files in Mozilla , it is not downloading fully.... it says 1second remaining, but not completing... But pictures and others are downloading fine i have downloaded many files earlier without any errors... torrent files are downloading fine in other browsers.............. plse help me ....................

Mozilla is not capable of this feature if you use U Torrent it will open automatically now when you open a torrent in Firefox you have to change the default program and you cannot click on use this for all. I had the same problem and I went to Chrome at it will open all torrents default hope that helps