Saving Youtube to Smartpone

If I want to watch something on YouTube, I can always 'save it for later' and watch it online with my iPhone. I know how to save a video using 'save' to different formats.


But how ( or can I ) can I save a video to my iPhone so I can watch it while I am [b]offline?[/b]


[b]I want to be able to save a video the same way I save an APP.[/b] I have several APPS that I can retrieve and watch offline, such as my exercise and Yoga APPS. I want to do that with a few meditation APPS that I have found on YouTube.


But, I have not figured out how to copy a video from YouTube and then save it to my phone.


How do I do that?

Thanks