Lets! Not let's! Lets is a form of word let, let's is a contraction of let us. Those are completely different words and are not inrerchangeable

https://youryoure.com/?apostrophe

> inrerchangeable

https://youryoure.com/?inrerchangeable

This is obviously a typo. Which can't be said about deliberately inserting an apostrophe into a word

You assume it is deliberate. It's more likely that it was a simple mistake.

They keystroke that produced the apostrophe was deliberable. The keystroke that produced not the letter I wanted was not

Despite the name youtube-dl can download from almost any platform.

I'm not sure about some of them since they are private only (you can't see anything without an account), but my go-to tool is JDownloader, that I run as a Docker container on a server