Watching full-length TV shows online is fast becoming a mainstream activity. About 33% of U.S. adult Internet users, or 58.9 million people, will watch full-length television shows online at least monthly this year, according to eMarketer. Among adults who already watch video regularly online, the rate is even higher -- 50%. Next year, the rate among these groups is expected to rise to 39% and 56%, respectively. To find out more about eMarketer's coverage of online video and consumer behavior digital marketing click here.