Complex sentence: Gaga announced that the music video for "Million Reasons" would be a continuation of the music video for previous single, "Perfect Illusion" and would be released on December 14,2016, afternoon on MTV followed by a worldwide release to Vevo shortly afterwards.
Split into simpler sentences: Gaga announced that the music video for "Million Reasons" would be a continuation of that for "Perfect Illusion". It was released on December 14,2016, afternoon on MTV followed by a worldwide release to Vevo shortly afterwards.