UPDATED: Make Bookmarkable v2.4
The newest version of Make Bookmarkable fixes a problem with files not being re-added to iTunes. Listen:
Recently, I had been seeing some reports of Make Bookmarkable mysteriously not working correctly for some users. The changing of the file type and extension of the selected tracks' files would go all right, but the file would not be re-added to iTunes' Audiobooks Library. After some investigation, the common thread of the problem was that the files were located on a MS-DOS FAT32 formatted external drive. Normally, Macs can deal with this. However, AppleScript cannot follow aliases of a file on such a drive unless the alias is the literal path. Make Bookmarkable changes the extension of files; such that an alias that earlier pointed to musicfile.m4a on a MS-DOS FAT32 drive doesn't recognize it when its name is changed to musicfile.m4b--unless you update the path of the alias to point to it. Do you follow?
Here's the thing: with an increasing number of Windows users switching to Mac and more Mac users working in Windows it's not out of the realm of possibility that they just plug their MS-DOS external drive into their Macs without re-formatting it. Also, as hard drive prices have gotten cheaper, users may be more apt to purchase a drive pre-formatted as MS-DOS. I know I've gotten a cheaper deals on MS-DOS formatted drives than Mac formatted, but, of course, I always reformat to HFS+. Considering this, I suspect I will be seeing this alias anomaly more in the future.