Support for more types of Youtube URLs

Came across links like this http://www.youtube.com/attribution_link?a=vWY_P7tULpw&u=%2Fwatch%3Fv%3DlmpBiqX_DTY%26feature%3Dshare (and http://youtu.be/CSyIrrKhJQQ while testing my modifications). The short links work with making the "watch/embed/v" part optional. Decoding the attribution links seemed the easiest way to make them work. So far, everything I've tried plays now.