What was wrong with the way it was?
It was broken before. You couldn't have different cover art for different TV Show episodes if they were in the same folder. So every episode of a particular show would have identical thumbnails, continually overwritten by whatever was newest.
Here is the problem. The moved artwork is no longer imported. And the originally imported artwork is now orphaned.
So I think maybe I can outsmart MC. This time I select both the video and the artwork and then move them together. Nope. Artwork at new location is no longer imported and tags have been lost.
I agree with some of this. Certainly all the stuff about when MC moves or deletes a video. The sidecar.jpg needs to move and be deleted at the same time.
Clearly, the problem with importing the files by default is that most users don't want to have their personal photos views "polluted" with a never-ending stream of cover art JPEGs. Sure, you can filter them out, but most people don't want to bother, and it needs to work right with the default views that MC provides. Their solution was to just not import the image files. I don't know if this was the right call. It is certainly the easiest solution. But now we have problems with MC not "tracking" the files well and moving them and deleting them with their "parent" files (same goes with the XML sidecar files, by the way, which aren't moved). Would their job be easier if they could just count on the files having some sort of database entry? Surely they
are actually tracking these files in the database somehow (if nothing else as a field in the parent files' entries).
On the other hand, to do it the other way, import them all and filter them out of the Photos views, they'd probably need to change the default views. That's fine for new users, but
every single current user of MC would need to modify their views to include the new filter. And, if they are imported files, then how will MC know that it is "okay" to move the file if the user decides to do a Rename, Move, and Copy on the file's parent? For all it knows, it is like any other imported image file. I'm sure, if they tried, they could figure a way around all of this, but I don't know if it is worth it... Clearly they decided no.
In any case, the "not importing" thing is easy to rectify. Auto-Import
will import these files if you watch for the right media types in your Video folder. All of my Cover Art files are being imported.