"Cingular is expected to announce on Tuesday an on-demand mobile TV service that runs over its new 3G wireless network. The service--called Cingular Video--allows viewers to select short three- to five-minute clips from 18 different channels, including selections from shows airing on the Cartoon Network, NBC and ESPN. Cingular has also partnered with media companies to offer exclusive content from sources such as Fox News, which will offer short clips of news, and HBO, which will offer clips of "The Sopranos," "Sex and the City," "Curb Your Enthusiasm" and "Entourage."Clips? I don't know that I want to watch just a clip. If I'm going to watch a video on my phone, chances are pretty good that I want more than a little clip. The exception, of course, is movie previews because there is nothing more available. The good news is that this service will be free of charge to Cingular customers who have the unlimited 3G data package ($20 a month).