/usr/share/gstreamer-1.0/presets/GstQTMux.prs is in gstreamer1.0-plugins-good 1.14.0-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | [_presets_]
version=1.6.0
element-name=GstQTMux
[Profile YouTube]
faststart=true
|