To add YouTube to Winamp, close Winamp and add the following lines to the bottom of the ml_online.ini configuration settings file (C:\Program Files\Winamp\ Plugins\ml\ml_online.ini):

ElementId11=8000
ElementIcon11=11002
ElementSubbed11=1
ElementName11=Youtube
ElementURL11=http://youtube.com/?cmd=mini

You should also remove this line: ElementID10=-1, save the file, and restart Winamp. When you do, YouTube should be embedded in your Online Services options.