libvdpau-va-gl is work-in-progress. While it works fine with Adobe
Flash Player, it may cause problems with other VDPAU-enabled
software. Therefore, it has not been enabled system-wide by
default.

You can either enable it by uncommenting the appropriate lines in
`/etc/X11/Xsession.d/20vdpau-va-gl` or enable only for some software
by setting `VDPAU_DRIVER` environment variable. For example, to enable
it in Chromium, start Chromium with the following command line:

    VDPAU_DRIVER=va_gl chromium

 -- Vincent Bernat <bernat@debian.org>, Sun, 16 Jun 2013 12:34:31 +0200