It's an old idea and is also how some anime fansub groups prepare their releases: the filename of each episode contains the CRC32 of the file inside [square bra

It's an old idea and is also how some anime fansub groups prepare their releases: the filename of each episode contains the CRC32 of the file inside [square brackets]. Doesn't really make much sense for BitTorrent uploads (which provides its own much stronger hashes), it's a holdover from the era of IRC bots.