My iPod Touch can no longer download Podcast Videos after upgrading to iOS4

After upgrading OS 3.1.3 to iOS4, My iPod Touch (2nd Generation) can no longer download such video podcasts as NBC News, CBS News, ABC News and Cranky Geeks from iTunes store. The moment the download starts, there is always an annoying prompt "this video cannot be played on this iPod".
It's really frustrating!!!

Same thing happening to mine also, still cant find a reason.
Message was edited by: glynn1019