This document has moved to gstreamer/docs/design/draft-missing-plugins.txt.

It can be found online at
http://webcvs.freedesktop.org/gstreamer/gstreamer/docs/design/draft-missing-plugins.txt?view=markup

Also see:
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstbaseutilsinstallplugins.html