Cercube for YouTube could be categorized as a YouTube user’s dream tweak, because it’s going to let you do things that the YouTube app probably doesn’t allow you to do, but nevertheless they’re things you, the user, have wanted for a long time.

Remove annoying advertisements from the app and enjoy watching videos.
Save videos offline so you can watch them on the go when you're far from home.
You can customize the look of the YouTube app according to your taste.