I’ve come across a rather interesting resource called FabChannel.com. FabChannel are providing quality video streams of whole concerts from legitimate sources, either licensed concert recordings from music companies such as Universal and V2 or professional recorded performances from Dutch based venues. The video quality is good enough that it could be expanded to watch full screen with only a small amount of graininess on a 1600x1200monitor with streaming through a Flash player. FabChannel’s performances cover a wide range of well known artists such as The View and Martha Wainwright, and they claim to have got over 900 performances available already.
The site also has integration with last.fm and can also provide useful artist bios etc. To generate income to pay for the service there are some adverts on the site, but they’re not annoying popup’s etc.