Don't really understand why the umps have to give a soft signal in these instances.What part of the image looked good to you? The bit where the ball is clearly on the ground without Root's fingers under it, out the bit where the ball is clearly on the ground without Root's hand under it?
I accept these calls happen in cricket. They can go either way; it's part of cricket, and one side feels hard done by. But on this occasion, M. Vaughan is right—that was not out.
Just refer it straight upstairs and let the 3rd umpire make the call.