Have a close look just behind your head at where the roll hoops pass through the body, You will have to lift the rubber seals a bit to do this. On some cars, the roll hoop doesn't line up very well with the hole in the bodywork causing intermittent metal-on-metal squeaking/rubbing sounds. The solution is to remove the roll hoop and open up the aperture in the bodywork. One or more of the rubber seals may need to be replaced too.
Check out this
THREAD for more info!
Update: I've just listened to your video and obviously the noise is related to back wheel rotation. As others have said, it could be related to one or other of the sprocket side fences (also mentioned in the above thread by the way). Remember that you can happily remove the outer fence and run without it. Alternatively, could it be a stone caught in the belt? Unlikely to be wheel bearing related IMO.
