&w=600 will make your youtube videos 600 pixels wide. For more info on posting YouTube videos to Wordpress click here
You can specify the width and height of the embedded video by appending
&w=...&h=...to the shortcode. It will automatically adapt to your theme’s content length and give you preferred dimensions.
- You can obtain a HD (high definition) version of the video–if it has one–by appending
- You can disable related videos by appending
- You can turn on the search box by appending