off screen pause

videooffscreen.js

play_in_view: function() {

        percent_of_video_visible = 0.2;

        function check_videos_in_view() {

            $('.ambient video').each(function() {

                var x = $(this).offset().left,
                y = $(this).offset().top,
                w = $(this).outerWidth(),
                h = $(this).outerHeight(),
                r = x + w, //right
                b = y + h, //bottom
                visibleX,
                visibleY,
                visible;

                visibleX = Math.max(0, Math.min(w, window.pageXOffset + window.innerWidth - x, r - window.pageXOffset));
                visibleY = Math.max(0, Math.min(h, window.pageYOffset + window.innerHeight - y, b - window.pageYOffset));

                visible = visibleX * visibleY / (w * h);

                if (visible > percent_of_video_visible) {
                    this.play();
                } else {
                    this.pause();
                }

            });

        }

        window.addEventListener('scroll', check_videos_in_view, false);
        window.addEventListener('resize', check_videos_in_view, false);

        check_videos_in_view();

        
    }