Early in its history , the series used guest hosts Grace Helbig , Hannah Hart , and Mamrie Hart ( no relation ) to help propel the series and its audience .
YouTube promotes the series through its Spotlight channel , as well .
Early in YouTube 's history , the series used guest hosts Grace Helbig , Hannah Hart , and Mamrie Hart ( no relation ) to help propel the series and its audience .
YouTube promotes the series through its Spotlight channel , as well .