my network won't let me see your video, i didn't know you added this already, nice!
yes, i mean the numbers folders like you say in that first sentence, it keeps it neat.
my idea, check if subdir '1' exists, then '2', up until '9'. this is possible in the fs code.
then choose a random number between 1 and 9, load that folder's files.
if a folder doesn't exist, for example there is 1 2 3 but no fourth subfolder, then only pick the random number from 1 to 3.
if subdir 1 doesn't exist, simply load the files in the normal /anim/ dir as usual.
no need for more data in the config file.
if you wanted to ensure you don't pick the same aniation/subfolder again next boot, then yeah you need to save data somewhere, but hopefully the randomness is ok