/usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/{DDC359D1-844A-42a7-9AA1-88A850A938A8} is in xul-ext-downthemall 2.0.13-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/../../../xul-ext/downthemall