I agree.... even on small pda screens or standard PPC 240x320 resolution you can watch movies and they look great. But a big TV screen is still nice sometimes, too.
The one thing I've found, though, is that it's easier to find opportunities to listen to audiobooks than it is to watch video. You can't really multitask as much with video.
I'm not sure how many adults will want mobile TV, but I hope it becomes popular. It would be reall great for sporting events or your favorite show when travelling. And teens are sure to love it. Just imagine when technology allows Tivo-like functionality on the handhelds!