When Flashgot adds one FTP folder to d4x (Downloader for X) should suppress the final slash of URL to work well in d4x. If it doesn't so, the download is added without name:

d4x is an old and discontinued downloaded manager but it's the only with mirror FTP folders and multi-thread actually for Linux. For this reason I believe it is important to maintain compatibility with it.
Regards.
EDIT:
I've modified it but I can't tested due to signature check. Could you please say me how can I build this add-on without signature check?
EDIT again:
I've done more tests and now FlashGot doesn't add the final slash.

Anyway, the problem continues. When I add one folder to download, d4x doesn't write the name of the download and this provokes that it download the contents of this folder but not the folder itself.