Though there already are scripts to do this, it doesn't seem they were made to be used outside of a Linux environment. Or at least I have no idea on how to do it, and I couldn't find anything on Google about it. I'm using Windows for now, but I assume the same applies for macOS.
subliminal should work fine in Windows and Mac, it's Python.
Install Python, pip install subliminal in prompt/terminal and you should be good to go.
Damn, that seems easy. Last time I checked the things I found felt unfriendly to people who don't know about code.
I installed Python, and then subliminal.

Then I used the code, but I instantly get"Download failed" error after pressing 'b'.
I believe the line that isn't working for me is:
subl = "/usr/local/bin/subliminal" -- use 'which subliminal' to find the path
I tried writing "which subliminal" on cmd, but nothing happened. I assume it must be prefaced by something related to Python, but I don't know what that would be. I did try finding the path by searching it myself, and ended on what seems to be the path: "C:\Users\User\AppData\Local\Programs\Python\Python35-32\Lib\site-packages\subliminal", but if I paste that into the line mentioned above, I get no response when pressing 'b', and when I change all the "\" into "/", I get the download failed error again.
edit: the script at the beginning states
local utils = require 'mp.utils'
I tried searching for "mp.utils" on my computer, but there was no such file. Maybe it's that?
Just for the record: on OSX it works the same as on Linux.
@firewater2:
I tried writing "which subliminal" on cmd, but nothing happened.
The Windows equivalent is in powershell: (Get-Command subliminal).path. Copy and paste the result of that into the script.
This is up to script authors, and as it was mentioned, it actually seems to work already.
@cmdrkotori
Thank you very much!!! That command provided the correct path (which is one I had actually tried, minus specifying subliminal.exe), and it works super nicely.
Sorry that I didn't mark this as question. I hope it serves as a good Google result for people who wanted to do the same thing!
For the record:
There is not only Powershell, the equivalent (more or less) to which on Unix in CMD is WHERE /?