Vitas is a Russian singer and he is an extremely talented singer. He said that he trains a lot and tries to sing perfectly.
He is a "countertenor", a male that can sing with a voice at contralto, or higher. (That is, mezzo-soprano and soprano.)
Many say he uses falsetto, as many other singers, to achieve this high pitch. However, his pitch is equivalent to that of a female's "whistle" - the highest vocal register - or simply, very, very high.
A good example of this high pitch is his "Opera #2".