/etc/sane.d/v4l.conf is in libsane-common 1.0.24-8+deb8u2.
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 7 8 9 10 | #
# In order to use the v4linux backend you have to give the device
# You can enable multiple lines if
# you really have multible v4l devices.
#
/dev/bttv0
/dev/video0
/dev/video1
/dev/video2
/dev/video3
|