i tried the "youtube" tags to encapsulate link to youtube,
But in fact, its not the link, but the integration code. On YouTube, you can copy link from "share button", or integration code from "integrate" button (buttons below the video when you watch it).
integration code copy
<object width="640" height="385"><param name="movie" value="http://www.youtube.com/v/Dj8aYQHhGFs?fs=1&hl=fr_FR"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/Dj8aYQHhGFs?fs=1&hl=fr_FR" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="640" height="385"></embed></object>
and the result when encapsulated with YouTube tags
[YOUTUBE]<object width="640" height="385"><param name="movie" value="http://www.youtube.com/v/Dj8aYQHhGFs?fs=1&hl=fr_FR"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/Dj8aYQHhGFs?fs=1&hl=fr_FR" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="640" height="385"></embed></object>[/YOUTUBE]