idk if im wrong but i guess that sequence of letter and number is just how the video was stored in the downloader.
like this for example
View attachment 94820
this is the id of the post in the website, but if i want to download the video, maybe with some website scrapping script, the script will probably download it using this link
View attachment 94821
both page has the same video, just one of them is in the atf page, while the other one is only showing the video, therefore it linked to the real name of said video
i guess it's possible to parse it, but for now i can't seem to find anything that tells me what all the number and letter was used for, fyi i've checked the .gif from your example, but by crosschecking from my list of animated post in atf, i can't seem to find it