Do dogs talk? What?
Tests over the years show that when dogs bark, they are often trying to mouth words that their mouths are not shaped to mouth. So, we don't understand them.
The test in the OP shows how researchers got around this problem.

it is indeed that Dog barks trying to say something , in the middle of the night they are calling us when they felt or being threaten .
so yes Dogs talks and they are loyal , very loyal to us.
I am a dog owner since childhood and up to now I have my dogs(though most of them already gone long)