How to do a fluid movement ?

[Wonse]

Hello !
I'm using Tnet tfor my game.  And, when i look another player walking, his move is "jerky". ( like this : http://www.youtube.com/watch?v=kRsRyxsye2k&feature=youtu.be )
i have tried to use the autosync on his transform (position & rotation), or, autosync on his rigidBody (position & rotation), or, Rthe TNRigidBody Sync. and it it always jerky.
What should i do ? My game is not  "quick & nervous", so, a little lagg is not an issue, but jerky movement, is a problem.

Should i calculate the interpolation between the 2 previous position myself, and lerp'ing it ? or someting like this ?

Edit : my player prefab have a rigid body, and his child has the renderer
Edit 2 : video added
Edit 3 :  chen i use a rigidBody sync, i got a spam on the console : "parameters do not match signature TNSyncRigidbody.OnSync (System.Int32, System.Single)" as an error

[ArenMook]

Looks like you are just synchronizing the position. You should instead synchronize the values that cause the player to move, and only sync the position every-so-often (say 2 times per second).