What is the random letters and number that I underlined in the

They are some kind of checksum.

It's a CRC.

>>185159
I think they're used to identify torrents when you download from IRC. Most large fansub groups like commie and horriblesubs use them.

>>185159
They're literally just a CRC32 of the file, as correctly stated in >>185165.

They're there for historical reasons, back when files were downloaded over FTP and Usenet, with no end-to-end verification. You'd CRC the file after you downloaded it, and if the CRC didn't match the filename, you knew the download went wrong somehow.

Bittorrent does all this automatically, and because it divides the file into small blocks and hashes each block, it can repair your download automatically.

There are 2^32 possible CRC32s, and (way) more than 2^32 possible files, so a CRC32 does not uniquely identify a file, and you can't "go about getting one" from its CRC32. [ed2khash does uniquely identify files, and you can get them by pasting the ed2khash into any edonkey client].

Any sfv utility can calculate a file's CRC32 and check it against the filename.

>>185177
Horriblesubs, quite famously, doesn't publish CRCs.

https://www.nayuki.io/page/forcing-a-files-crc-to-any-value

Not really even a good identifier any longer. I've seen some releases where they do custom CRCs as well.

>>185401
They were never a good identifier.

That's never what they were for.

Historically, they were for spotting bad downloads, and we just kinda kept them because why not?

If you don't intentionally munge them, then they are in fact a decent way of distinguishing v1, v2, v3s of an otherwise identically-named file.

But they were never designed to detect intentional corruption, only accidental.