/etc/X11/Xsession.d/20vdpau-va-gl is in libvdpau-va-gl1 0.4.2-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | # To enable the use of libvdpau-va-gl as the default VDPAU driver,
# uncommont the following lines. See
# `/usr/share/doc/libvdpau-va-gl1/README.Debian` for more details.
# [ ! -f /usr/lib/$(arch)-$(uname -s | tr '[A-Z]' '[a-z]')-gnu/vdpau/libvdpau_va_gl.so.1 ] || \
# export VDPAU_DRIVER=va_gl
|