Chain/gear problem? clank noise

[Hapi]

Friend got a problem with chain or with gear, there is some clank noise, here is video:
[nomedia]http://www.youtube.com/watch?v=K2yfZXV2KfY[/nomedia]

any suggestions ?

tnx

 

[Denver_FZ6]

It appears you are initially rocking bike back and forth while in first gear, but I can't tell from the video if the noise is normal gear lash or not.
Since noise stops once shifted to neutral, I'm not suspecting the chain. Also, if it was chain issue, I would expect noise to follow bad link on chain as rear wheel is rotated.
Have you checked chain tension? Are there other symptoms while riding?