Editor, Video: HTTP error and blank image tag when uploading video, Macnchrome

Video upload is a mystifying pain.

Related: #28367 Video upload failure is a dead end.

#28367, #4-4, #beta, #chrome, #editor, #macos, #upload, #video

Customize: preview site responsiveness, Macnchrome, iPad Air, iPhone 6+

A brief visual survey for #31195 with WP 4.4-alpha-33848 and Customizer UI Experiments 0.1.

#4-4, #alpha, #chrome, #customize, #customizer, #customizer-ui-experiments, #desktop, #feature-plugin, #feature-preview-responsiveness, #ios, #macos, #phablet, #preview, #responsive, #tablet, #visual-survey