I have recently inserted the Flash badge for Twitter in my site; but the original code offered by them is not valid HTML. So why not use code that passes validation? Here it is:

<div style="width: 176px; text-align: center">
 <object width="176" height="176" title="what am I doing... (Twitter badge)" type="application/x-shockwave-flash" data="http://twitter.com/flash/twitter_badge.swf">
  <param value="http://twitter.com/flash/twitter_badge.swf" name="movie" />
  <param value="color1=255&type=user&id=USER_ID" name="flashvars" />
  <param value="high" name="quality" />
  <param value="twitter_badge" name="name" />
  <param value="always" name="allowScriptAccess" />
  <param value="transparent" name="wmode" />
  <param value="http://www.macromedia.com/go/getflashplayer" name="pluginspage" />
 </object>
 <a style="font-size: 10px; color: #0000ff; text-decoration: none" href="http://twitter.com/USER_NAME">follow USER_NAME at http://twitter.com</a>
</div>

And the result is (using my own user data):

Just some comments:

• Don’t forget inserting your actual USER_ID and USER_NAME (and your preferred color1 parameter if you want to); you can get them at Twitter’s badges page.
• The & strings are not part of the URL but the correct way to write ampersands in HTML code; more information about ampersands in URLs can be found here.
• More information about inserting Flash using valid (X)HTML can be found here.