StereoTube just outdid themselves with their latest update to their YouTube & MP3 player BlackBerry PlayBook app. This latest v4.0 update adds the ability to download YouTube videos to your PlayBook with the option to save it as an MP4 file or simply an MP3 song. They have also added some speed enhancements along with a new UI for playlists. They also improved things like being able to rename playlists.
Check out StereoTube for $1.99 in App World