Compatible with iPad on iOS 5. iPhone support coming soon
PwnTube is a tweak that enables you to download videos from the native YouTube app on iOS 5.x and add them to the iPod library
To download a video, open it in the YouTube app, in the inline mode, tap on the "Download" button in the top left corner. You'll be notified when the download is done. The video will automatically be imported to the iPod music library.
See larger Screenshots below..