volumedown_for_niconico.user.js

// ==UserScript==
// @name           Volumedown for niconico
// @namespace      http://d.hatena.ne.jp/nastack/
// @include        http://www.nicovideo.jp/watch/*
// ==/UserScript==
(function(unsafeWindow){
	var VOLUME = 10;
	var meta = document.evaluate("//meta[@name='keywords' and contains(@content,'\u97F3\u91CF\u6CE8\u610F')]",
		document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
	if (!meta) return;
	var flvplayer = unsafeWindow.$("flvplayer");
	var Inter = setInterval(function (){
		flvplayer.ext_setVolume(VOLUME);
		if (flvplayer.ext_getVolume() == VOLUME) clearInterval(Inter);
	}, 100);
})(this.unsafeWindow || window);