Attention: The script is not working anymore, because the service of the site youtubia.com is not functioning as well.
Youtube/Google is constantly trying to make the download of videos more difficult, so a tool like this script has to play catch up, and that's not pretty. Don't download unless you want to solve the problem.
With this service you can search for YouTube clips and add them to your playlist.
It seems you need at least amarok 2.0.2 for this script to do its job.
If someone has a patch to make it work with pre 2.0.2 versions, that would be great, too.