No, the sounding of this Persian piano is different from the sounding of the Byzantine music. When I wrote the "style" is similar I meant that the musician played on the piano with only two fingers. The Byzantine organs (and all old organs) had no keyboards. These organs were small and the musicians used the palm of their hands to close the pipes of the organs.

This is unlikely - as far as I know the earliest mentioning of a drone is from the period near the fall of the Empire.

By comparison of the music of various people living today in the territory of the Byzantine empire I suppose that one of the organs played the main melody and this melody has single melodic line (no harmonization). The second organ served as an accompaniment - at times this could be simply a drone. Here is another youtube clip that demonstrates one possible method for the accompaniment (but the sounding again is very different from the sounding of the Byzantine music):Mugham from Azerbaijan. Notice that the singer is improvising but this doesn't mean the musicians have to use some trivial accompaniment like the drone. Something similar happens with the moder jazz music.