checkHostName => isValidHostname

This works on mobile too as far as I can see so please enable it in this case too.

This regex is faulty, for examples it matches this, but shouldn't: `'https://www.a.com/watch?v=SADub7W22Zg'.match(/^.*(youtu\.be\/|v\/|u\/\w\/|embed\/|watch\?v=|&v=)([^#&?]*).*/)`

- Please remove the width and height as that should be controlled by your CSS now. - Please remove the double/triple spaces for example around `class="video-iframe"` or `frameborder="0"`

What do we need this padding for?

`videoID[2].length == 11` is not necessary if your regex is correct.

Please could you change this to use only one regex. I think videoIDRegex should already give the ID so the `key` doesn't seem necessary.

Please move this to the `plugins` object below because your plugin is setup like a regular markdown-it plugin, unlike the rules in this object.

Please use a template literal to format and indent the HTML string - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals Any reason why you chose width 560? I guess it makes sense to set a min and max width, but otherwise could you make it shrink and grow with the container? Could you document these properties and are they necessary? `accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture` For example, for me the video doesn't even auto-play (and I don't think it should) so the autoplay property maybe is not needed. I don't know about the others.

Please don't silence exceptions, it leads to poor quality software since errors get undetected and never get fixed. Secondly, the way I understand this code is like this: if the user adds a YouTube URL, display a video player. If they add any other URL, display nothing. Or am I missing something? You didn't add automated-tests yet but did you test with regular URLs in the app?

You've got a small typo. Perhaps: 'Enable video embedding'

Normally this should be implemented in TypeScript, as mention in CONTRIBUTING.md. But let's say in JS is fine too, provided the implementation is correct.

rule should be called "video", not "embedvideo".

"tokenize" means converting a string to a stream of tokens. That's not what this function does.

That solution is not optimum as you're unnecessarily parsing the whole Markdown document even though it's already been parsed by markdown-it. Markdown-it will produce a stream of tokens, which you can hook into to provide alternative rendering. In your case, you could hook in link_open and, if you detect that the href is a YouTube URL, display your iframe code. Please have a look at the markdown-it doc for more info.