Hide Flash animations until clicked

Introduction

Flash can be either helpful or annoying. This procedure will let you hide Flash animations until you click on them, which saves you from loud or flashy ads. It works on Firefox and related browsers. The technique is from here, I just cleaned up the placeholder and simplified the directions. When you're done, it will look like this:

Directions

The userContent.css file is used to apply CSS rules to all documents you see. The file lives in your profile's chrome directory. On Windows, this is something like:
  C:\Documents and Settings\username\Application Data\Mozilla\Firefox\Profiles\meq9qe9g.default\chrome\userContent.css
On Linux:
  ~/.mozilla/firefox/m9fychwe.default/chrome/userContent.css
Open this file in a text editor, and add the following rule to override Flash animation objects:
 /* Prevent flash animations from playing until you click on them. */
object[classid$=":D27CDB6E-AE6D-11cf-96B8-444553540000"],
object[codebase*="swflash.cab"],
object[type="application/x-shockwave-flash"],
embed[type="application/x-shockwave-flash"],
embed[src$=".swf"]
{ -moz-binding: url("http://dsss.be/noflash/ctv.xml#ctv"); }
All flash animations will be be replaced by the javascript at http://dsss.be/noflash/ctv.xml. If you want to change the placeholder, just download mine, modify it, host it somewhere, then change your userContent.css file to point to your file instead of mine.