I have made more tests...
if i add this :
Option "Composite" "Disable"
in xorg.conf, totem still have tearing but the problem is present on the upper part of monitor (mplayer is fine).
So i have removed Composite Option in Xorg and i have played some video.
Well, the problem is always present if video is on upper part of monitor (totem and mplayer).
If i enabled "compositing manager" in metacity problem is in all video (everywhere in the monitor).
Any ideas to solve the problem ?