Note: This question is about download URLs, not software. The question "How do I download a YouTube video?" deals with software.

What exactly changed for YouTube download URLs a few days ago? How should YouTube download URLs be formed now?

The following URL used to work (downloading this Flash video to disk) but no longer works since the change:


Note: the following information is only to illustrate the problem. I am only interested in the information about how to form download URLs.

This change affected quite a few tools. Here are leads from some Firefox plug-in homepages:

From Video DownloadHelper 4.7.4, 2010-07-22:

"As many of the users noticed, Video DownloadHelper does not work well on YouTube since today. This is due to a very recent change at YouTube. We made a fix that seems to work ok. "

From Easy YouTube Video Downloader 3.4, 2010-07-24:

"Please update to latest version 3.5 in sandbox to get it working again with latest Youtube changes"

From YouTube Downloader, 2010-07-24:

"YouTube has updated their website in a way that breaks YouTube Downloader 2.5.6 and older. We are working on version 2.6 which fixes this problem."

Related: "How do I download a YouTube video?". Some of those tools may be broken now!

  • I don't see any change in the source code. Maybe it's a slight change, but the videoplayback link is still there.
    – Vortico
    Commented Jul 24, 2010 at 22:57
  • @Vortico: do you have a direct URL to that source code? Commented Jul 25, 2010 at 0:06
  • (Placeholder for Andrew's comment: "you forgot to say what the change was and the code solution.") Commented Jul 25, 2010 at 0:53
  • OH! Sorry about that, I misunderstood. What I meant to say is that you can still download the FLV or MP4 (HTML 5) by opening the source code of the video page and searching videoplayback.
    – Vortico
    Commented Jul 25, 2010 at 2:17
  • 2
    For example, the link to the FLV of the video you posted is v12.lscache4.c.youtube.com/…
    – Vortico
    Commented Jul 25, 2010 at 2:18

2 Answers 2


I am unsure what changed, but I suspect YouTube changed their URLs so you can not get a video without matching cookies. This prevents 3rd party sites from showing you ads and giving you download links.

I can tell you this link (pasted at the very bottom), which I got from your video, WORKS for me. However if I paste it in my other instance of Firefox (which has different cookies for the site) this link does NOT work.

I suggest using a userscript. I like YouTube Enhancer.

If you need to do this in code I do see the link(s?) in var swfConfig =


to make it easy for me to read I did a full escape using this handy script.

http://v12.lscache4.c.youtube.com/videoplayback?ip=,expire,ip,ipbits,itag,algorithm,burst,factor,oc:U0dXRVFRTl9FSkNNN19JS1JB&fexp=903205,906501&algorithm=throttle-factor&itag=34&ipbits=0&burst=40&sver=3&expire=1280160000&key=yt1&signature=2F2BB59B9BA3E6AB62CEE47F597D7A4D96002893.03196019F468211FAA4E492F7F5B1951951AEAF9&factor=1.25&id=0d85b9d05e36b2cf&title=Tom Lehrer CHEMISTRY element song


I found another great browser script to use with GreaseMonkey.

It is called YouTube Links. It is available here (archived). And here is the source code.

I have chosen this, because it works without derouting to an external downloading webapp.

enter image description here

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