Here's a quick and simple way to embed a clip here. Start the video playing at the location where you found it.
1. Right click on the screen while it's playing.
2. Select the third option on the list -- "Copy Embed Code".
3. Paste that code into a post here and the clip will embed. The embed string will look something like this:
"< div style="position:relative;height:0;padding-bottom:56.25%">
Note: If you hit preview, you will not be able to see the embedded YouTube clip previewed. It will only show up after you actually submit the post.