Rated 5 out of 5 stars

Thank you for this extension. :) I have just found and install this extension while I was searching Firefox's FTP server modified dates timestamps. Orbit Downloader (so it is my favourite download manager for a long time :) ) can do this too. :) It preserves modified dates of files are downloaded but if you don't do Pause+Start. I have just tested this extension witt my favorite software and you may look the result: :)
http://s5.postimg.org/6mtlq05zb/Firefox_modified_date_of_downloaded_files_extens.png

Thank you for reading my comment.

Adding: I have just tested it for one of my favourite videos too via savefrom.net (YouTube video directly download site without a software and it worked perfectly. :) I am so happy. :)
Note: I read the comments of the another friends, my Firefox version I tested is old, 3 years old. Firefox 17.0 (20 November 2012)