Embed a Youtube video in Github markdown

It's not really possible to properly embed a video in a Github comment, pull request or issue like it's possible for images for instance. So if you want to put a video in a Github pull request (I do that quite often), you have to upload it to a video hosting service like Youtube and then you can put the link in the description. This is not what I would call embedding a video but at least it's simple and effective.

Lately, I discovered on Stackoverflow a much better solution where the simple text link to the video hosting service is replaced by a thumbnail generated by the video platform. In markdown, for Youtube this gives:

[![Alt text](https://img.youtube.com/vi/VID/0.jpg)](https://www.youtube.com/watch?v=VID)

Of course, VID should be replaced by the actual Youtube video id. This is still not embedding a video but that's a bit nicer and a much better incentive to click to watch the video :-) The only problem is that it's a tad long to type and to remember. That's why I decided to write a Greasemonkey script to simplify that. Actually, at first I wanted to write a super simple bookmarklet but Firefox has a very annoying issue where bookmarklets are broken on Content Security Policy enabled website like on Github :-(

Anyway, the Greasemonkey script is available on Github in dpobel/github-add-youtube-video. To use it, you first need to install Greasemonkey and then just load the addvideo.user.js in your browser, it should ask if you want to install that script. After doing that, the Github markdown editor should get a shiny new button that is able to transform any Youtube URL to the previous code snippet, here is the script in action:

Screencast of github-add-youtube-video Greasemonkey script
Screencast of github-add-youtube-video Greasemonkey script

If nothing is selected in the textarea, hitting button will just prompt the user for a Youtube URL to embed. This script should also work in Greasemonkey clones for Chrome, though I did not test it.