This is more than likely an issue with the actual original video. We render out videos using Apple's H.264 codec at 1080p. The only way we'd render a mashed video at 720p is if the content itself was 720p. There is a setting for the iOS camera that allows you to record at 720p or at a higher frame rate that turns on 720p automatically. Also, keep in mind most front facing camera record at 720p not 1080p.