Beryl на Gentoo, XSync extension : failed

Решил на Gentoo поставить Beryl. Использовал эти how-to:

http://gentoo-wiki.com/HOWTO_nVidia_GL_Desktop_Effects
http://gentoo-wiki.com/Beryl


Из /etc/X11/xorg.conf:

Section "Extensions"
Option "Composite" "enable"
EndSection

Section "Device"
Identifier "device1"
BoardName "GeForce 7600 GT"
Driver "nvidia"
Option "DPMS"
Option "UseEvents" "false"
Option "RenderAccel" "true"
EndSection


При попытке переключиться на Beryl с metacity:

**************************************************************
* Beryl system compatiblity check *
**************************************************************
Xlib: extension "XVideo" missing on display ":0.0".
xvinfo: No X-Video Extension on :0.0

Detected xserver : NVIDIA

Checking Display :0.0 ...

Checking for XComposite extension : passed (v0.3)
Checking for XDamage extension : passed
Checking for RandR extension : passed
Checking for XSync extension : failed

No sync extension
134701434 screens detected.
Currently we cannot guarantee that Beryl will work correctly with multiple X screens.
Using the --no-context-share command line option can help.
Please report any success to the beryl developer mailing list. The list can be found at lists.beryl-project.org