In Firefox the image specified by the poster attribute of the VIDEO
tag remains on screen until the play button is pressed. However in the Webkit browsers (Safari a
If you can get away with not preloading the video you can set preload="none" on the video element. In Safari this results in the poster being displayed.
Safari on iOS probably sets preload="none" as the default to save bandwidth, while the desktop version preloads unless you explicitly tell it not to.