I suspect it's the belts, and probably a frozen tensioner bearing, if I just were to take a guess. But that definitely isn't carb noise. That almost sounds like a gear whine, but being so high pitched, I'm going to guess the timing belts.The engine in the video has a whine that is changing pitch with rpm but not throttle position. The flatslides have a certain whine that you can hear when opening the throttle but not at idle. That whine on the video is something else, possibly from the belts? I think the 900ss is not supposed to sound like that. I wouldn't buy the bike unless the cause of the whine is found.