You're not alone in that, Norwegian Blue. A poster on the Technet thread observed a November patch Tuesday resurgence of the issue - thinks it's apparent here too.
From what I have gathered so far, the issue is connected with the handling of metadata when Explorer scans files, generates thumbnails - no Microsoft confirmation of that, that I'm aware of though. Seems to me that which patch Tuesday sends the damage (August
to November) may be down to MOV versions/variations - this has affected multiple versions of iTunes, Quicktime and similarly iPhones and pads of different ages; all at different times apparently.
One thing I did not try - curse my soul as I really should have thought of this before I took off the updates - go into control panel/ system/ advanced system settings/ performance, and uncheck show thumbnails. Might have been informative if it was enough
to stop the crashes/errors and allow associated playback of MOVs. Can't test this now, as the laptop has gone back to client. Have you tried that Katep_don't?
I'd be inclined given the November link, to remove, one at a time, the November patches until hopefully, the error disappears - or take the lot off and if the error's cleared, put them back one by one, to identify the culprit. Bit of a slog and time consuming,
but may deliver results; or considerable frustration. If removing the November stuff doesn't work - take of the two earlier updates too, to see if that finally clears it.