This week's big TV event was unquestionably the season premiere of "Lost"; lots of people have, over the course of the previous five or so years, become huge fans of the show. But new stats imply that very few of them sat in front of computer monitors on Wednesday, rather than televisions on Tuesday, in order to watch the two-hour episode. Nielsen took a look at why people watch online TV, and the leading reason doesn't have much to do with convenience or fewer commercials.