New Chronology: Understanding the Gregorian and Julian Calendars

In the 7th episode of the 'Forgotten History' series on the radio station GOVORIT MOSKVA ('Moscow is Speaking'), aired on December 26, 2015, Gleb Nosovsky explains the difference between Gregorian and Julian Calendars from the New Chronology point of view. Why do Orthodox and Catholic holidays of Christmas and Easter fall on different days?