Valid Youtube links
Dec 2013
Detecting valid Youtube links:
(http://)?(www\.)?(youtube|yimg|youtu)\.([A-Za-z]{2,4}|[A-Za-z]{2}\.[A-Za-z]{2})/(watch\?v=)?[A-Za-z0-9\-_]{6,12}(&[A-Za-z0-9\-_]{1,}=[A-Za-z0-9\-_]{1,})*Dec 2013
(http://)?(www\.)?(youtube|yimg|youtu)\.([A-Za-z]{2,4}|[A-Za-z]{2}\.[A-Za-z]{2})/(watch\?v=)?[A-Za-z0-9\-_]{6,12}(&[A-Za-z0-9\-_]{1,}=[A-Za-z0-9\-_]{1,})*