Latest Youtube update on iOS adds iMessage sharing button where recently watched video are ready to be shared with friends and families and the great thing is you can watch it within the iMessage app.

A new Youtube share button is added at the bottom of the iMessage app while in conversation. When you tap it, you will see all your recently watched Youtube videos. To share it with your friends, all you need to do is tap the new Youtube share buttonlook for the video that you want to sharetap it and hit send. It’s that simple.
And when you receive the video shared using the same tool, you can directly watch it using the iMessage app without having to quit it and without having to launch the main Youtube app.
Get Youtube from Appstore and is available for free to download.