/usr/lib/x86_64-linux-gnu/libavdevice.so.53 is in libavdevice53 4:0.8.17-0ubuntu0.12.04.2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libavdevice.so.53.2.0
/usr/lib/x86_64-linux-gnu/libavdevice.so.53.2.0