This video discusses the possibilities of this being a flying monk that lived in the area. I do admit that it does have a lot of similarities to the monk. Also, yes, some aliens could fly like this, but not most.
For example, energy beings easily move about without the need for legs. If this is indeed a local monk, then we now know for sure, he was never human and that he never died, but has technology for living forever and is still to this day watching over his home of San Petersburgo.