I have no idea, but it's that easy to find an editor as a content creator.
Video editing is a primo skill in today's economy, and most everything doesn't need a savant editor with tons of experience. Youtube ain't the Academy Awards. It's not even a television commercial. There just needs to be something on screen that matches what the person is saying. Sure, good editing will stand out, but I guarantee a large part of what you watch is just B-roll video game footage that matches the topic being discussed. That's usually plenty enough.
But the thing is, it's a quantity-driven business. There's just so much to edit, even in a tame video, and it just takes so much effing time. Like seriously, I would bet Billy's 50 minute video took AT LEAST 15 hours of finding footage, music, graphics, editing. So when it can be done 100% remotely, outsourcing it seems smarter and smarter for anyone in charge of a channel/brand of a reasonable size. Most every big channel and Smash streamer has a dedicated editor and it's just another business expense.
Don't even get me started on anime content, and 10 second clips and green Simpsons, jfc.