/usr/lib/ is in ruby-gstreamer 2.2.5-4build1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/ruby/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.3.0/
/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/2.3.0/gstreamer.so
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/gst.rb
/usr/lib/ruby/vendor_ruby/gst/
/usr/lib/ruby/vendor_ruby/gst/registry.rb
/usr/lib/ruby/vendor_ruby/gst/element.rb
/usr/lib/ruby/vendor_ruby/gst/controller-loader.rb
/usr/lib/ruby/vendor_ruby/gst/plugin-feature.rb
/usr/lib/ruby/vendor_ruby/gst/bus.rb
/usr/lib/ruby/vendor_ruby/gst/caps.rb
/usr/lib/ruby/vendor_ruby/gst/bin.rb
/usr/lib/ruby/vendor_ruby/gst/structure.rb
/usr/lib/ruby/vendor_ruby/gst/element-factory.rb
/usr/lib/ruby/vendor_ruby/gst/base-loader.rb