Is there an easy way to download youtube videos onto my iPhone?

All the other methods I have found are complicated and require a jailbroken phone. I don't have and don't want a jailbroken iPhone.

App called musictube

1.Sync your phone to iTunes on your computer
2.Open Youtube and search youtube to mp3 in google
3.Copy and Paste the YouTube Videos link in the Youtube to Mp3 bar
4. YouTube to Mp3 should have a a way to download video instead of just audio
5.Open Downloads on your computer and drag your selected files into iTunes
6.Sync and enjoy

Those two articles can give you a hint to download youtube videos onto your iPhone without jailbroken.