Also they seem to require session cookies, I had all cookies blocked and I kept getting the "Invalid Code" page, so that means I'd have to send the cookie as well. If I keep downloading junk from them I may spend time to figure it out.

I've been playing with this script some, and I may update it it, but DF really sucks in my opinion.

If there is a mirror link, then the script works great.
But if there is no mirror, then you can show the hidden captcha form using this Style Sheet code...

  #download_url {display: block !important}
  #img_code_form {display: block !important}
  #img_code_block {display: block !important}

However, you still have to wait until the timer just about runs out. And I haven't yet got this to work in Greasemonkey, probably because their script keeps hiding them with .style.display = "none". But they are really slow anyway and I try to avoid them if there's any alternative.

The ads are really annoying, and I just block the ad servers, but I might figure out how to get rid of that crap as well, but it's cross-site scripting so it may be easier to just block those ad sites. Or maybe just remove everything that's not part of the download code, that may work. Also I think I can get the download link instead of submitting the form (using GM_xmlhttpRequest). I copy the download URL from Mozilla download manager and use another download manager, so I'm sure it would work.