Ability to download part of a file; for example on a 1400MB file you may need to download the last 500MB of it.
It is useful when you have a broken file (especially video files) in hand and now you wish to download its remainder, join them and get the complete file.

Or maybe there will be a way to import a broken file from hard drive into FDM and make it download the remaining bytes by specifying the final size of the file and which position to put the available partial file.
Thx.