Sometimes you think you're mind is playing tricks on you. I have that sometimes. E.g. I have a Popcorn Hour (Networked Media Tank) which holds movies and series I watch. Bits and Bytes come and go on that machine. Thing you've seen are deleted, and replaced by new content. But over the 'years' it seemed to hold less and less content. Oke, movies have increased in size (10-20GB per movie is nothing nowadays). So I didn't really think much of it....
Until I started transporting the content with Transmit instead of FileZilla. Transmit was configured to show even the hidden files, and hidden files it showed. I found 4 hidden temporary pureftp-upload files of almost 32GB each. The timestamps on those files differed from late last year to a couple of months back
.pureftpd-upload-<some random string>
The problem was that I couldn't remove them from the Popcorn, but I really wanted my 120GD of free space back. Turned out that the FTP daemon on the Popcorn was locking these files. Reboot of the popcorn didn't help.
The way to remove them was to stop the FTP daemon on the Popcorn in the menu, and access the device through SMB (or another protocol you can use), and make sure that you can see hidden files.
Select the files and press delete, and they should be gone. After that you can re-enable the FTP service if you like.