Still problem?
How about following the next ?
su
mknod /dev/video0_for_100000 81 0
chown 10000:10000 /dev/video0_for_100000
exit
# LXC config
lxc.mount.entry = /dev/video0_for_100000 dev/video0 none bind,optional,create=file
# lxc.cgroup.devices.allow = c 81:* rwm
As long as I know, “lxc.cgroup.devices.allow = c 81:* rwm” does not work for unprivileged container.