about that...

you can easily check when your download has progressed to certain point, by looking at this folder (Vista & 7):

c:\Users\{username}\Documents\My Games\FINAL FANTASY XIV - A Realm Reborn\downloads\ffxivpatch\4e9a232b\patch\

There you will see a file chunk that keeps growing in file size. After a certain point that file will be gone, which means it has been installed onto game folder, and new file appears with growing in download size. Then it repeats again and again until all finished, meeting total download quota on the launcher.

Still... I'm going back to my original request, to have patch download auto-resumable, and not making that current downloaded file chunk needs to be repeated from beginning when error occurred.