It is possible that your ISP blocks the YouTube videos. You can try different DNS servers.

If you live in India then see:

• http://www.medianama.com/2014/07/223-world-cup-2014-472-websites-including-google-docs-blocked-in-india-following-sony-complaint/
• http://www.nextbigwhat.com/delhi-high-court-orders-block-google-docs-several-websites-297/
• http://delhihighcourt.nic.in/dhcqrydisp_o.asp?pn=119642&yr=2014

I have attempted different DNS servers, including Google DNS, and this method did not fix my issue. As I previously stated, my ISP likely does not block the vidoes, as these videos still work on Google Chrome and other devices connected to the same network. I also do not live in India, I live in the US.

A couple of of a longshots, as I don't use YouTube enough to be familiar with it myself.

1. I wonder if you could have set you tube settings to HTML5, if that is still an option.
   Try one of the 60% that work and right click the video player is it actually playing in flashPlayer ?
2. Maybe some security related software, an addlocker / scriptblocker is interfering with the playing.

Both videos that are working and videos that are not working are playing in Flash, as when I right-click the videos, both give an "about flash 14.0..." button as well as settings which change the flash options. I do use a combination of noScript and adBlock, which blocks java scripts from running without permission and ads respectively, however I have noScript set to allow the scripts on youtube and even when both of them are disabled the videos still won't play. As well, even when firefox was reset to factory conditions with no add-ons what-so-ever, videos would still not load.

Can you post a couple of links to working videos and a couple to problem videos. Someone may be able to notice something that causes a problem.

I was going to ask Are you or any of these videos originating in the Indian SubContinent ? I ask as I know India currently has a problem with a lot of blocked content due to Judicial action. Should that be the case there may be workarounds but I see that was already covered in posts above.

We do not have your troubleshooting information but if you are using Windows (> xp) it would be worth trying with FlashPlayer's protected mode disabled.

• http://kb.mozillazine.org/Flash#Disabling_Protected_Mode_in_Flash_11.3
  • https://forums.adobe.com/thread/1018071#TemporaryWorkaround

I have attempted disabling protected mode in Flash, but to no avail. As far as I am aware, none of the videos I have watched and experienced issues with were from India. The following are videos found from searching YouTube in YouTube that either work or do not work.

Working YouTube Videos: YouTube Complaints 2014! from Barely Political: https://www.youtube.com/watch?v=_y0SCQJvA1c

20 Misconceptions About Sex - mental_floss on YouTube (Ep.212) from Mental Floss: https://www.youtube.com/watch?v=nSNoiAnUnH0

Casting a Fire Ant Colony with Molten Aluminum (Cast#043) from AnthillArt: https://www.youtube.com/watch?v=IGJ2jMZ-gaI

YouTube Challenge - I Told My Kids I Ate All Their Halloween Candy 2013 from Jimmy Kimmel Live: https://www.youtube.com/watch?v=RK-oQfFToVg

Rewind YouTube Style 2012 from YouTube Spotlight: https://www.youtube.com/watch?v=iCkYw3cRwLo

Would You Recognize a Missing Child? (Social Experiment) from DmPranksProductions: https://www.youtube.com/watch?v=DI7OHCmIsAE

Non-Working YouTube Videos: YouTube Rewind: What Does 2013 Say? from YouTube Spotlight: https://www.youtube.com/watch?v=H7jtC8vjXw8

Killer Clown Returns Scare Prank! from DmPranksProductions: https://www.youtube.com/watch?v=hHjGtBnSv50

INSANE Domino Tricks! (Hevesh5 & MillionenDollarBoy) from Hevesh5: https://www.youtube.com/watch?v=ARM42-eorzE

Killer Clown Scare Prank! from DmPranksProductions: https://www.youtube.com/watch?v=8xSNiPx791A

FROZEN- Let It Go Sing-Along | Official Disney HD from Disney UK: https://www.youtube.com/watch?v=L0MK7qz13bU

As well, here are two foreign (Japanese) videos which either do/do not work.

Working YouTube Video: 「If」歌ってみた【柿チョコ】 from s8660620 https://www.youtube.com/watch?v=j7RG-O1TCXE

Non-Working YouTube Video: 【合唱】　千本桜！！！ from finalshion: https://www.youtube.com/watch?v=ohUbKy5XG4I

As you may noticed, there are cases that some videos work while others that are from the same YouTube uploader do not work.

I tried one and it works for me with the Flash player and with the HTML5 media player on Linux.

• https://www.youtube.com/watch?v=ARM42-eorzE
• http://www.youtube.com/html5/

I requested the use of the HTML 5 player, however the video simply showed an error for the HTML 5 player, then switched to the Flash player and showed the same error. However, the website claims that my browser does not support the following items, as shown in the picture attached to this post. Is this normal for Firefox, or is the unusual? Either way, might help with solving something.

I may see a fleeting message, but the problem ones I tried from the list above did work in both FlashPlayer and HTML5. (I also usually use Linux)

(Unless I had a script blocker active)

Must admit I am out of ideas at the moment.

I attempted disabling NoScript whilst running HTML5, however to no avail. It also might be worth noting that videos which worked also worked in HTML 5. Thanks for the support so far, at the least we have been able to narrow down some things.

Sorry I am clutching at straws here, but unless cor-el comes up with something better:

As troubleshooting steps it may be just worth reconfirming a few facts. Problematic videos in the same machine same router and DNS server with

1. An alternative browser such as Chrome
2. Using new additional Firefox profile, all plugns except Flash disabled, and using Firefox SafeMode and FlashPlayer protected mode disabled. extensions disabled _{already disabled in safe mode, as is hardware acceleration}.
3. As 2 above but starting in Windows Safe Mode with Networking.
4. As an alternative to a clean install of Firefox install and test out the thirdparty unofficial build Firefox Portable as an additional browser. In fact it would be worth testing with Portable Firefox ESR which also rules out recent regressions in Firefox as the cause.

• Use http://portableapps.com/apps/internet/firefox-portable-esr

Two other avenues for tackling this issue

With all of that done it seems odd you have problems if others do not. At the moment I am not even seeing any fleeting errors. I am wondering how we capture those errors. Do they show up with details as JS errors in the browser console

• (Ctrl+Shift*J) https://developer.mozilla.org/en-US/docs/Tools/Browser_Console
• Not sure I would understand them even if they did !
  but it may help someone should there was a unique error on only the none working videos.

May be worth reporting on the Adobe's support forum seeing if or how they may be able to help.

• https://forums.adobe.com/community/flashplayer/using_flashplayer

I note seeing suggested solutions/causes as: interfering addons, reinstalling FlashPlayer, hardware/driver or hardware acceleration issues, ramping up of video resolution to maximum definition on some videos.

N.B. I will edit thread title Was

Youtube videos claiming, "An error has occured, please try again later." on every video.

To

Youtube videos claiming, "An error has occurred, please try again later." on most videos.

Just another thought.

If you have the same error in HTML5 on the same YouTube links it is looking like a site or script etc error rather than specifically just FlashPlayer.

You can also check the Web Console (Firefox/Tools > Web Developer) for errors to see if that gives a clue of what is wrong.

• https://developer.mozilla.org/Tools/Web_Console

After this post I will be going on a camping trip until Wednesday. When I return, I shall attempt all potential solutions posted. To re-confirm John99...

1. An alternative browser such as Chrome

-In Chrome, the videos do work.

 2.Using new additional Firefox profile, all plugns except Flash disabled, and using Firefox SafeMode and FlashPlayer protected mode disabled. extensions disabled already disabled in safe mode, as is hardware acceleration.

-I have attempted this before, but to no avail.

3. As 2 above but starting in Windows Safe Mode with Networking.

-Also did not help.

4.  As an alternative to a clean install of Firefox install and test out the thirdparty unofficial build Firefox Portable as an additional browser. In fact it would be worth testing with Portable Firefox ESR which also rules out recent regressions in Firefox as the cause. 

-Yet to be tried.

I have attempted almost all of the things listed in your post but the Portable Forefix ESR. I have yet to have used the Portable Firefox ESR, however when using Firefox on other computers connected to the same network, videos which do not work on this computer do work in those computers. The following pictures are what the developer console (or maybe this is the web console, not sure which is which, but I'm sure someone can tell) displays for the two japanese videos. The first two images are images of the developer console for the video which does NOT work (error1 & Error2) while the second two images are for the video which does work (work1 & work2) . In both cases, NoScript was disabled.

Also, the last few lines of the developer console in both the error and working cases repeat themselves indefinitely (probably until the video ends).

It happens in Chrome too. It also happens on completely different PC in this house.l It happens when I changed the DNS servers. It happens when I did all the things that everyone says to try- like in OP. Nothing works. And it is completely random, so one day it is one vid, then next the vids that were broken work and new ones that worked before do not work. So you can't just give someone a link and say, does this work? Because most likely it will for them, but that doesn't mean the Youtube is not currently broken.

BTW this site is more broken than Youtube! 80% of the time I get error messages and messages saying site is undergoing maintenance and also sometimes all the buttons are greyed-out. It is a miracle anyone can post anything at all!

It took 5 tries to post this! WTF.

EDIT Here check this out https://productforums.google.com/forum/#!topic/youtube/axsb7XPieK0

From glancing at the link in the post above

• https://productforums.google.com/forum/#!topic/youtube/axsb7XPieK0

Looks like there were Google issues that eventually got reported and possibly fixed.

• That thread fragment was within
  https://productforums.google.com/forum/#!categories/youtube/playing-and-watching-videos

As for this site being down it does sometimes have issues but is fairly reliable. To check consider looking at

• http://status.mozilla.com/#table_hist (scrollable)
  • http://status.mozilla.com/11627/141983/support.mozilla.org
• And third party tests such as http://www.isitdownrightnow.com/support.mozila.org.html