"C:/Users/UserName/AppData/Roaming/Mozilla/Firefox/Profiles/gwg92pil.default/chrome"
BTW, you may download the userContent.css with ad block and then add marquee block to its end. CSS ad block is better than the add-on.
Also add this to block flash, again better than the add-on:
embed[src]:not(.ucContent):not([src*="nicovideo"]):not([src*="ytimg.com"])
{
content: -o-skin("Attachment Video") attr(src);
-o-link: "javascript:document.activeElement.className+=' ucContent';void(0);";
-o-link-source: current;
border: 2px dashed #080 !important;
font: normal normal normal 10pt sans-serif !important;
padding: 1px !important;
display: inline-block !important;
height: auto !important;
}
Be aware, WXC may bess up above codes, so if it does not work, try find them on the web.