How to download YouTube videos to your iPhone?

How to download YouTube videos to your iPhone?

Copy the Youtube URL to a video downloading site, I use www.convertfiles.com or keepvid.com if convertfiles doesn't work. Save it as a MP4

Download Vdownload from the iTunes Store. You may not be able to get YouTube but at least you can DL from dailymotion.com

There's this app called iTube where it doesn't download the videos but it saves them in the app so you can watch them without Wi-Fi or play the audio when your phone is locked (like music)
you can make playlists too it's pretty great

I know an app which is called smth like YouTube to iPhone converter.
The developer is DVDVideoSoft, just google for it.