The weather Channel is currently broadcasting LIVE on their YouTube channel. I'm not sure if this will continue, but I suspect that it is just temporary and related to tropical storm Sandy coverage, and the live feed will end after the storm passes.
Even if it is only temporary, it does bode well for the future. Perhaps future major weather events will receive similar live coverage.
Here is the live channel embedded for your convenience:
For Roku users, you can use PlayOn to stream the video from your computer to your television. YouTube is included in the free version of PlayOn.
You can download PlayOn FREE here.