WordPress Plugin: Youtube
This plugin is no longer supported. I recommend using Smart YouTube PRO instead, which I now also use on this site.
Download the plugin, extract it to your wp-content/plugins directory and activate it just like any other wordpress plugin. Afterwards, you can include a youtube video on your posts or pages by writing this (without quotes):
You’ll find the necessary id in the address of the video. A typical address looks like this, the id is highlighted in bold: http://www.youtube.com/watch?v=8DHOZW_8OPk