Video Capture Renders Black W/Metal

From AnswerHub:

Under OS X 10.11.4 using Metal on an AMD FirePro D700, captured video using the editor's built-in video capture tools is black. It doesn't matter if I attempt to capture images or video, the result is the same. However, if I use an external tool video is rendered*. I can still take screenshots using the OS's built-in tools, however the engine can't seem to capture video or screenshots.

Under 4.10 and OpenGL, this works just fine.

1. Open ContentExamples in Editor
2. Load Matinee level.
3. Select Matinee 4.2.
4. Create a movie.
5. It'll be black (or assert if the Metal validation layer is on)