Or with your iPad, there is a TubeDownloader app. I think that is what it is called. I don't know why Apple approved it, but you can download YouTube videos with it. Or, if you have it jailbroken, there are a few YouTube downloading apps like MxTube.
Unfortunately, my app TubeOrganizer does not have downloading capabilities, because Apple said they would reject such apps.
Check out
http://www.ipadintouch.com/how-to-download-youtube-videos-to-your-ipad/
Free app lets you download 4 videos, but the paid is unlimited.
Good Luck
Mark