split?

i have a site named profile.php where i want to replace the following:

<youtube>http://www.youtube.com/watch?v=yoXE031j8d0</youtube>;

into:

<iframe width="420" height="315" src="http://www.youtube.com/embed/yoXE031j8d0" frameborder="0" allowfullscreen></iframe>



i know i could use str_replace to replace

<youtube>

into

<iframe width="420" height="315" src="

and

</youtube>

into

" frameborder="0" allowfullscreen></iframe>


... but i need to know the URL so i can check if it really is a youtube video.

Thanks alot for your time

regards noob

Web programmer and intelligence don't go very well together in one sentence.