Hi Cristole
You are right, this solution doesnt catch ( url =
www.youtube.com )This is my video( / url ) links.
If you need to use tags, i think plugins like allvideos will be the choice if your users are familiar with tags.
Also, about the signature, yes, if you write the url in your signature (without tags) , it will be auto embedded. However if you dont want the video to be embedded, just the link shown you can use the normal -url- tag which is another advantage of not replacing links created with the url tag
Hugo