/usr/share/gtk-doc/html/gstreamer1.0-vaapi is in gstreamer1.0-vaapi-doc 0.5.7-0ubuntu4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/gtk-doc/html/../../doc/gstreamer1.0-vaapi
/usr/share/gtk-doc/html/../../doc/gstreamer1.0-vaapi