1. Go to Youtube and pick a video you like
2. Copy the special key for the video
-----watch?v=<HERE">-----
3. Paste it into <YOUR KEY GO HERE"> in the code below
<iframe src="https://www.youtube.com/embed/< YOUR KEY GO HERE >" width="560" height="315" frameborder="0"></iframe">
4. Put the code with your key in it to the post cotent
Example:
<iframe src="https://www.youtube.com/embed/Os4Zztck0Ek" width="560" height="315" frameborder="0"></iframe>