For the lack of Coverflow alone, I've avoided iTunes 11 like the plague. Some obviously do not care about that, but with version 10.7 I've had little trouble with an external library—so perhaps another reason to avoid version 11 for now.
Music is stored locally on the internal drive, but space limitations have long since dictated most video moved to an external hard drive. In this instance a Time Capsule not otherwise used for Time Machine backups, although I cannot see why that would make a difference one way or another.
But can report that the files and their associated cover art are invariably accessible when the external drive is mounted
(with cover art always viewable in iTunes, external mounted or not). And I have to pay no particular attention to it, turning off the computer, un-mounting, remounting and so forth in no particular order. Any movie or TV program only has to be located once
, when first moved from the internal drive to the external. It will then display the exclamation mark (!), and simply a matter of pointing to its new location—but again, only once the first time.
Sometimes—seemingly at random and for no accountable reason—the associated artwork for a movie or TV program will vanish but then unaccountably reappear. No idea why, although playing the file in question seems to bring it back, or it will just reappear later on its own. But this minor in the grander scheme of things.
Perhaps that was the default setting, do not recall, but in iTunes preferences, under Advanced, both "Keep iTunes Media folder organized," and "Copy files to iTunes Media folder when adding to library" are checked, selected, and active.
IF one has any different experience, and iTunes 11 responsible, then Apple owes you a big apology. And you can thank them for the inconvenience by taking the trouble to revert back to iTunes 10.
Reports have it many love the new version of iTunes. Fine. To each their own. Nothing wrong, either, with having the experience work all the more swiftly and efficiently. Although I've never had much trouble in that regard with version 10. Indeed, never much cause for complaint. I doubt I could say the same with version 11—at least and until Apple decides to "fix" what they should not so abruptly have messed with.