I'm sure there is a great bash option but my bash is rubbish.
A quick python script would work.
From the datetime module you could use fromisoformat() method to get the date then use the strftime() to get your Year-month-day format. All this after reading the directories contents with the os.listdir() or os.walk() loops. You could parse the filenames for IMG/VID using if "VID" in file_name logic. You could strip the date from the file_name before using datetime with string slicing. Lastly you can use the os.rename() method to rename the file.
These steps are a bit out of order. But the ingredients are there. With a bit of search engine magic you should be able to work up a script. I would set up a testing folder and test it well before using your script on things you don't have a back up of.
