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can not play youtube videos

  • 34 replies
  • 2 have this problem
  • Last reply by Rob1911

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Can not play youtube videoss in Firefox, Chrome or any browser except Tor.

If I download the video it will play. But, I can not play a live cam unless I use Tor.

I have had this problem for 3 years and no one can seem to figure it out.

Error is: Failed to find video url.

Thanks, Rob

All Replies (20)

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Hi Rob, I'm puzzled when you say you can download YouTube videos but not play them normally. Downloading is not a built-in feature of YouTube.

What kind of downloader are you using? Is it possibly a proxy that intercepts your Firefox and Chrome connections, but is bypassed by Tor because Tor tunnels past it?

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Thanks. What would you recommend setting my proxy setting to?

Downloading question: Using video downloadinghelper as add on to Firefox.

Concerning the proxy answer here is what I did.

Went to to locate a free proxy to use.

Selected and put in my url in the form at the bottom of page and pressed Go.

Youtube videos played.

So, I would think my proxy settings need to be changed but to what and still be secure? It presently uses the system settings.

rob-terri@robterri-desktop ~ $ env | grep -i proxy NO_PROXY=localhost,,::1 no_proxy=localhost,,::1

rob-terri@robterri-desktop ~ $ wget -q -O - \ > | sed -e 's/.*Current IP Address: //' -e 's/<.*$//'

I take there is no proxy set on the system. I use a cox modem, and a netgear FVS124G router on Cox internet.

Thanks for all you help!

Take Care!


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Hi Rob, I'm not recommending you use or not use a proxy, I'm just trying to understand your current setup.

Is a "live cam" different from a regular YouTube video? Maybe you could give a sample URL in that case.

Also, could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

  • "3-bar" menu button > "?" button > Restart with Add-ons Disabled
  • Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement? (More info: Diagnose Firefox issues using Troubleshoot Mode)

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Try to disable IPv6 (check for other possible causes as well).

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Will play: When they did the live cams they only played in Tor.

Will not play in Firefox. Will play in Tor. "failed to find video url"

Any videos on YouTube.

Playing Firefox in Safe Mode with addons disabled. Does not make any difference. YouTube videos and live cams do not play. Only thing differ is the error message "error try again" and it takes a full 3 minutes for circle in middle to quit spinning.

Disabled IPv6. Made no difference.

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These crazy cubs are trying to eat a metal hiking stick someone dropped!

But I digress.

The nps page uses Flash, while the first explore page (and framed YouTube page) uses the built-in HTML5 viewer. Does your Firefox show native support for H.264 on YouTube's test page here:

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Show support for HTMLVideioElement.

Does not show support for: H.264,

WebM VP8, 

Media Source Extensions, MSE & H.264, MSE & WebM VP9

Do I need to enable H.264?

Thanks, Rob

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Hi Rob, I'm not sure whether to read that as no support for anything, or no support for particular items. Anyway, you can check whether settings have disabled support for those formats as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste med*ena and pause while the list is filtered (this will match all the true/false preferences in the form media.something.enabled)

(3) If the the following preferences are bolded and "user set" to false, double-click them to restore the default value of true

  • media.mediasource.enabled
  • media.mediasource.mp4.enabled
  • media.mp4.enabled
  • media.ogg.enabled
  • media.webm.enabled

Note that some video downloaders may take over management of these settings if they cannot capture from a site using those formats. If you find these settings keep getting flipped to false, check your downloader settings to see whether you can prevent that in there.

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All the following items are set to true/enabled. Did not have to reset.


Checked the downloader settings did not see anything that pertained. Thanks, Rob

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That's puzzling. Could you try the videos on the following test page:

Scroll down past the obsolete table to find three players. Which ones work, if any?

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All three videos play.

H.264/MP4 plays WebM plays Ogg/Theora plays

Thanks, Rob

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I'm having trouble thinking of a setting that would only affect YouTube. If you go back to about config and put youtube in the search bar, do you see anything site-specific in the filtered list of preferences?

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Here is a copy about:config for youtube. The only thing that looks suspicious is under "capability.policy.maonoscript.sites: but I am no computer expert.


capability.policy.maonoscript.sites; about: about:addons about:blank about:blocked about:certerror about:config about:crashes about:home about:memory about:neterror about:plugins about:pocket-saved about:pocket-signup about:preferences about:privatebrowsing about:sessionrestore about:srcdoc about:support blob: chrome: mediasource: moz-extension: moz-safe-about: resource:;false























extensions.{7b1bf0b6-a1b9-42b0-b75d-252036438bdc}.description;YouTube High Definition is a powerful tool that will let you play all YouTube videos in High Definition automatically.;false


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Hi Rob, "capability.policy.maonoscript.sites" is your NoScript whitelist. Assuming you use (or have used) NoScript.

Nearly everything relates to an extension, so the Safe Mode test should rule out those items as the potential culprit.

I don't recognize this one:


However, I have that set the same way, so probably not an issue.

Can you think of any mechanism whereby certain domains used by YouTube for the live cam video might be blocked at the system level, affecting all browsers other than Tor (which tunnels past them)? This could involve your firewall, hosts file, other mechanisms for filtering by host name. In particular these are used for the bears video:

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Checked to see if router has anything blocked. It listed as a trusted domain.

Checked modem - nothing.

Wife has laptop connected to modem and router and it plays youtube videos.

Checked iptables - everything is accepted.

checked hosts file - nothing blocked.

Search around for the ones used by the bears video - nothing: Except /home/rob-terri/Downloads/TOR/tor-browser_en-US/Browser/browser/chrome.manifest


The second one comes up with nothing.

Thanks, Rob

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How do I access "mozilla-release" to get to "dom", to "base", to "nsObectLoadingContent.cpp", to line "1462"?

Thanks, Rob

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If you try to hit this URL in Firefox and Chrome, do you get Google's 404 page ("The requested URL / was not found on this server. That’s all we know."):

To dig into the error on the bears page, for example, could you try using the Network Monitor to see whether Firefox is successfully retrieving the files from the manifest server and whether it is able to retrieve any of the video fragments from the other googlevideo addresses. "200" is a successful retrieval; other codes have a variety of meanings and potential causes. (Screenshot example attached.)


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Rob1911 said

How do I access "mozilla-release" to get to "dom", to "base", to "nsObectLoadingContent.cpp", to line "1462"?

That's a link to a section of the Firefox 53 source code that involves fixing broken URLs for embedded videos. Since you have the same issue when viewing videos on YouTube itself, I don't think that is related to your problem.

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If you try to hit this URL in Firefox and Chrome, do you get Google's 404 page? Answer: Yes.

In the Network Monitor: On YouTube. Status File Domain Cause 200 orange triangle 304 scheduler.js www, script orange triangle 304 base.js www, script orange triangle 304 www-core-vfl-CwO8d.css www, stylesheet orange triangle 304 wwww-player.css www, stylesheet 200 204 200 orange triangle 304 base.js www, script Gray dot --- generate_204?conn2 img Gray dot --- generate_204 img orange triangle 304 www-hitchhiker-vfl-Nn88d.png img orange triangle 304 pixel-vfl3z5WfW.gif img 204 Gray dot --- videoplayback?...... xhr Gray dot --- videoplayback?...... xhr

On the bears video I get all status 200,

200 chunk_1491796023_731af1d23f.flv objectSubdoc 404 teststyles.css stylesheet When playing the three videos all in the 200s status.

Went to Status 200 Domain padlock with diagonal line. document

red square 400 qoe?event=streamingstats&fmt=244&afmt=251&cpn=M img

Went to Gray dot --- videoplayback?clen=26408993&signatu xhr

Thanks, Rob

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