bash-3.2$ beryl
Xlib:  extension "XVideo" missing on display ":0.0".
xvinfo: No X-Video Extension on :0.0
**************************************************************
* 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
4234907 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