When is a commercial must-see TV? In my house, it’d be whenever a Mucinex ad hits the airwaves. (Quick! Press pause! That funny little blob of phlegm and his bride are on again!) But let’s be honest, in a Tivo/DVR world, it’s getting harder and harder for advertisers to find a captive audience. Which makes ABC’s latest initiative kind of genius. Next month, the network will begin a two-month trial in which viewers can watch free episodes of Lost, Desperate Housewives, Alias, and Commander in Chief on their website the day after an episode has aired. Viewers will be able to pause, but won’t be able to fast-forward through the commercials embedded in each episode. Or, to paraphrase Mr. Mucus: They’re not goin’ anywhere!