If your iphone is not currently jailbroken, then I am afraid to say that it is not possible. If your phone is jailbroken, go to cydia, add the ihacks repo, then install yourtube 2, it is a built in youtube video downloader for your youtube app.
There currently no way to do that right now. You can download videos from iTunes then sync them to your iDevice, Or you can jailbreak your iDevice.
There is a Tweak called YourTube that allows you too download Youtube Videos from the Youtube.app
Can you retrieve deleted text messages on Android? Yeah, this video will show you the full guide for Android text message recovery. Don't hesitate and recover deleted textmessages from Android 4.0, 4.1, 4.2, 4.4, 5.0, 5.1 and more versions right now!
Not only can you recover SMSmessages from Android backup but also can recover Android SMS messages without backup. This video is showing you how to recover deleted sms messages from Android.
Some common situations that lost text messages you can recover from:
1. accidentally deleted texts on your android phone
2. lost text messages after Android 5.0 updated or other Android upgrade.
3. save textmessages from water damaged, crashed, broken or smashed Android phone
4. Android deleted text messages randomly by itself
5. Factory restore Android phone.