It's Der Voghormia, or Lord Have Mercy.
Here are the words:
Der voghormia (repeat four times)
Amenasoorp Yerortootyun, door ashkharhis khaghaghootyun.
Yev hivantatz pujhushgootyun, nunchetselots arkayootyun.
Lord have mercy. (repeat four times)
All Holy Trinity, give peace to the world.
And healing to the sick, heaven to those who are asleep.
The melody was written by Gomidas Vartabed. He lived one hundred years ago and his music is much beloved by the Armenian people. During the Genocide, as the Turks were gathering up the intellectuals in Constantinople to deport and kill them, they say Gomidas Vartabed began singing this hymn. They say the Turks stopped as he sang and could only stare and listen, as they had never heard anything so beautiful. They took him and the others, though, and it was only through the mediation of influential Non-Armenians that his life was spared.