Complex sentence: To allow that the producer created a series of basic/introductory videos that introduced the characters and their environment and then published a site where audiences could add comments and proposals (comments were also permitted via SMS).
Split into simpler sentences: To allow that the producers published a series of basic/introductory videos that introduced the characters and their environment to the audience. Then they also published a website where audiences could add comments and proposals (comments were also permitted via SMS).