2002 50TLRB Rattle under the flywheel...

[25Johnny]

My sons' 50HP Yam has a rattle under the flywheel at low RPM. Seems to fade as throttle increases. Is there something loose on the flywheel?

 

[25Johnny]

Ok, here's a video. Any ideas?

https://www.youtube.com/watch?v=ArAVPRK-ctw