To state that someone is blessed is hardly venerating him or her.
The Bible states that many people are blessed, and indeed they are. That doesn’t mean they are to be objects of worship.
This excerpt kind of helps in understanding how they view Mary and why she is deemed very important in their religious view:
“When the Archangel Gabriel spoke to her, the Blessed Virgin could have refused God’s request to bear His Son. Her positive response to the Archangel Gabriel plays an important part in salvation. As St. Irenaeus of Lyon wrote, Mary is the second Eve, whose obedience liberates humanity from the consequences of the disobedience of the first Eve. For this reason, on the Feast of the Nativity of Mary, Orthodox Christians sing, “ … the Mother of Life, who is the renewal of the creation of Adam and the recall of Eve, the fountain of incorruption, the liberation from corruption, through whom we have been deified and delivered from death, is born of the seed of David, dispersing darkness.” Mary could have refused to bear Christ, but she chose to obey God.”
http://www.antiochian.org/node/17079
It seems they really do believe that Mary could have refused God and then Humanity would not have gotten a saviour.
True. Veneration takes these forms: