This tests:
1. Initially, toolbar is visible, "Show Controls" button is not.
2. After the video controls fade out, they can be shown when VoiceOver or a keyboard user clicks the invisible "Show Controls" button.
3. When the video is paused, the controls become visible and the "Show Controls" button is hidden.

PASS
FAIL: "Show Controls" button is not hidden initially.
FAIL: Toolbar still around after mouseout.
PASS
PASS
FAIL: Toolbar should not exist
PASS
FAIL: Button should not be visible.