Sorry, maybe I've explained it a big wrong. The <before> and <after> should mean that there is some random text.
So instead...
<before>http://www.soundcloud.com/artist/track<after>
<before>www.facebook.com/page<after>
<before>www.youtube.com/watch?v=1234567<after>
<before>www.somesite.com/bla<after>
...it could also be like this...
Blablabla http://www.soundcloud.com/artist/track
www.facebook.com/page is my page
Try www.youtube.com/watch?v=1234567 for my video
Check http://www.somesite.com/bla.
I would like to automatically insert different wordpress shortcodes inside a user generated post, exchange urls with videos or soundcloud widgets and create regular links from all the other URLs and emails.
Thanks for helping guys.
greetz,
Mat