Bug 874055 - [Video] Activity played videos are missplaced in Peak device

Simplified code by aligning the video with CSS with some small js help.
Added new fullscreen missing id to `view.html` (to unify code).
Also added black backround to body tag in order to avoid white flashes.

Tested on Peak and Unagi like device on both portrait and lansdcape mode using videos from sdcard and youtube.