MacOS – folder copy in Finder labels it as incomplete, though copying is completed

The index.bdm file was probably named that way on the original card, but appeared as INDEX.BDM when mounted on the Mac. FAT32 is not case-sensitive, and OS X's file system code (specifically the NSFileManager class) programmatically presents FAT32 contents in uppercase. OS X can open AVCHD content, even with a filename in lowercase, from case-insensitive media, like FAT32 or HFS+ in its default, case-insensitive mode.

However, when you copied the AVCHD content to a case-sensitive filesystem, the true nature of that lowercase filename becomes visible (it doesn't get renamed as lowercase, it simply gets revealed as lowercase to begin with!). OS X / QuickTime get confused by the lowercase name, and you get the dreaded "CANNOT OPEN".

The fix is to ensure that all the AVCHD-standard files and folders are in uppercase. As you see, the folder tree above the INDEX.BDM files loses its special status, but the INDEX.BDM file can be double-clicked to open the AVCHD browser. Just as importantly, editors like FCP X and FCP 7's Log and Transfer window will properly see the media even on the case-sensitive filesystem.

I encountered the same thing copying AVCHD to a Linux-based NAS with a case-sensitive filesystem. In my case, my Panasonic cameras will write an INDEX.BDM file when I erase all clips or format the card in-camera, but if I erase just one or a few clips, the file gets written as index.bdm. Since Apple's code breaks with mixed-case AVCHD filenames, I'm writing a utility to walk my folder trees and make sure everything is uppercase, grumble grumble...

I have two suggestions. My first is to try creating a folder called .Trashes elsewhere and moving it such that it would overwrite the original folder; it's possible that this would leapfrog the problem (I used a similar method to fix a problem I was having a few months ago).

Alternatively, if the external drive is FAT32, have you tried booting a Linux distro from a USB drive and using that? Alternatively you could plug the external drive into a Windows machine (Boot Camp/VirtualBox?) and see whether that can delete the offending folder.