/usr/share/doc/libquicktime-doc/index.html is in libquicktime-doc 2:1.2.4-10+deb9u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libquicktime-doc/qt4l_index.html
/usr/share/doc/libquicktime-doc/qt4l_index.html