We've been looking at this for a year, and have had no joy with it. There are no cheap solutions to this.

The company we use is Unique Media TV - Live and On-demand Webcasting, Media Hosting and Video Production for streaming live cameras in wmv format (yeah, I know). Don't host any media with them so I don't know if they manage flv's.

We are currently looking at our own server and flash media server, which is quite expensive option, but is only a one off cost.