You Tube is very much an extra tv channel. Just check the number of times it is quoted in the tv and print media though very often it's minor criminal types filming their activities and wondering why they got caught.
The UK Politics Channel was launched last week by Gordon Brown with a video (1 min 16 seconds).
So far we have the Labour Party, Webcameronuk (worth a visit), Green Party, Sinn Fein and Respect. A cross-section but where are the nationalist parties, and maybe the Co-operative Party could think about joining in too with some short, inexpensive talking head footage. I'll stress the concept short - some of the material available to view is nearly 15 minutes long which doesn't suit squinting at a PC with other distractions going on.
UK Politics Channel
