It looks like all the videos are safe (that I can tell). For some as yet unknown reason, all the missing files that are causing the error were moved from their original folder into a similarly named folder inside the site's .css folder. I have no clue how or why this has happened, but I know I didn't do it.

Knownhost will move these files back into their original folder, then they should all work. They will investigate how this happened, when, etc.

Everything should be good now. The videos should work as usual.

Indeed, they're working again. Excellent...