preventlargeflash.user.js

// ==UserScript==
// @name           preventLargeFlash
// @namespace      http://orezdnu.org/
// @include        http://*
// ==/UserScript==

(function(d) {
    var tags = [ 'object', 'embed' ];
    var t = 0.95; // threshold
    var wait = 300;
    setTimeout(function() {
        var c = {
            w: window.innerWidth || document.documentElement.clientWidth,
            h: window.innerHeight || document.documentElement.clientHeight
        };
        if (!c.w && !c.h) return;

        var resize = function(node, which) {
            var size = c[which.substring(0, 1).toLowerCase()]*t;
            if (node['offset'+which] <= size) return;
            if (!size) return;
            node[which.toLowerCase()] = size + 'px';
            node.style[which.toLowerCase()] = size + 'px';
            return size;
        };
        var remove = function(node) {
            var parent = node.parentNode;

            var p = d.createElement('p');
            p.style.borderStyle = 'dashed';
            p.style.borderWidth = '0.2em';
            p.style.borderColor = '#cc3333';
            p.style.backgroundColor = '#ff99cc';
            p.style.color = '#333333';
            p.style.textAlign = 'center';
            p.style.fontWeight = 'bold';
            p.style.margin = '1em';
            var msg = 'A flash has been removed.';

            var a = d.createElement('a');
            a.appendChild(d.createTextNode('>> restore'));
            a.addEventListener('click', function() {
                parent.replaceChild(node, p);
            }, false);
            a.style.marginLeft = '2em';
            a.style.cursor = 'pointer';

            p.appendChild(d.createTextNode(msg));
            p.appendChild(a);
            parent.replaceChild(p, node);

            return true;
        }

        var r = {};
        tags.forEach(function(x) {
            r[x] = {};
            var arr = d.getElementsByTagName(x);
            for (var i=0; i < arr.length; i++) {
                var f = function(which){ return resize(arr[i], which); };
                var w = f('Width'); var h = f('Height');
                if (w||h) r[x][i] = w || h;
            }
        });
        tags.forEach(function(x) {
            var arr = d.getElementsByTagName(x);
            for (var i=0; i < arr.length; i++) {
                if (r[x][i]) remove(arr[i]);
            }
        });
    }, wait);
})(document);