I've gotta admit, I'm skeptical.
Oh, exorcisms are real, no doubt, and there are people that do them. (I've seen one, actually.)
But *never* in the Scriptures was any demon cast out in the name of Mary. The only name that is above all names, in heaven, under heaven, and under the earth is Jesus.
Thus when this guy says he tells demons "the Madonna is on my side" I've gotta raise an eyebrow. The Madonna did not defeat them, Jesus did, so that's the name they have to submit to.
Is Mary on our side? Sure. But evil spirits don't care because she is not in authority over them.
How would you know? Ever talk to an evil spirit before?
Fr. Amorth admits himself that "we can be saved only in His Name" (An Exorist Speaks Out, 22). However, in his conclusion to the book, he describes Mary's role as "an instrument of the divine plan," in the war against evil. Also, in a chpater where he describes the behavior of demons, he talks about how demons react to certain holy names. Obviously, demons are going to hate the Holy Name of Jesus. But most of them also cannot say the name of Mary, saying "she" or "your Lady" to indicate Mary. If the demon posessing a person is high-ranking, they can say these names, but "always followed by horrible blasphemies."
If you want to turn from a skeptic to a believe, I suggest you read his book.
Keep in mind he didn’t say that he used Mary’s name to cast him out, but merely that she is on his side. Mary is in fact the mother of Jesus. Jesus was raised by and is obedient to Mary. He also mentioned that he tells the demon to face Gabrielle who is an arch angel. Though Gabrielle is most certainly not God or Jesus, he is definitely on God’s side. Any friend of God to a demon would be feared.