Idefinitely don't abbreviate.
what happens when a year from now you're looking through your movies trying to decide what to watch and you see FW?
it's not like it's a LOTR or something that is commonly referred to be an acronym. If i came across a FW dvd I would assume it's a storage dvd full of past firmwares for me drives!
i use a sharpie and print full titles on the dvd itself.