There seems to be some amount of uncertainty over how to embed a youtube video onto this site. I'll attempt to demonstrate.
First, you want the youtube.com link and not the one for youtu.be If you post up a video, click the link they give you and it will be a youtube.com link in your browser. Copy that to post into this site.
Now that you have your link, it's time to embed it onto the page. Using a link to a video that Jim Pettijohn put up, it should look like this (without the bold text):