Iframe / Embed Test on WordPress Page

Embed Code Test - Works


& Iframe Code Test - Doesn't work
[iframe src="http://www.youtube.com/embed/4qsGTXLnmKs" width="100%" height="500"] &

Advanced Iframe Plugin - Doesn't work
[advanced_iframe src="/www.youtube.com/watch?v=4qsGTXLnmKs" width="100%" height="600"]