You did all this code yourself, DrMeepso ? Wow! How on Earth did you figure this out?
Looking at it now, I can't make head nor tails of half of it, and it also appears to be different to the video example.
This looks like it listens to a Discord, while your video version posts to a Discord.
Also, "SendDiscordMSGToMainChannel" never appears to be called.
I'd love to work on this more with you if I can twist your arm? :D
EDIT - Yeah, I seem to be hitting the CORS issue, too... The Discord API references and instructions are pretty terrible. Doesn't seem to make sense that I can connect to Twitch with relative ease, but Discord is a confusing mess.
Yeah the post is quite old and the video was filmed pretty much the same day i got it to work so it has been though some changes.
As for discord.js it has decent documentation here docs
when i first started trying to get it to work i did have to change the endpoint. so you may have to look into that.
but that pretty much all i can help with because i made it so long ago.