Media Preview in Page Info may not meet TBB expectations for media handling
Media Preview seems to allow what should be disabled via internal settings, and may not be under the same controls as other parts of the browser.
Examples with gstreamer at #18782 (moved); an additional test was performed using the internal setting for disabling images (permissions.default.image) and they still showed up in Media preview. Not just in the Address section as URLs, but as actual displayed pictures. Any need for eliminating tracking pixels, for instance, might be subverted by this.
The objective here is to check where Page Info/Media Preview's settings are, whether they are under the control of settings at all, and most importantly to find out if anything they do can contradict user-intended/expected levels of security.