Media Embeds
https://twitter.com/nacin/status/319508408669708289
This post tests WordPress' Twitter Embeds feature.
http://wordpress.tv/2009/03/16/anatomy-of-a-wordpress-theme-exploring-the-files-behind-your-theme/
Posted as per the instructions in the Codex.
http://www.youtube.com/watch?v=SQEQr7c0-dw
Learn more about Embedding Youtube in WordPress.