Things I tried:

-Reinstalling FireFox

-Uninstalling Flash

-Scan for viruses with MSE

-FireFox safe mode

i've got the same problem with every youtube video now, after firefox updated itself to 14.0.1

take a wild guess if it's annoying the **** out of me or not? :o @x64 xp

had the same problem since upgrading to 14.

tried downgrading to 13 but for some reason the problem came with, probably because i didnt do a full uninstall and erase of settings.

anyway, go here http://www.youtube.com/html5/ and opt out of the trial.

if you read the script error it always has to do with html5 so i figured that was the issue.

I see the same happening with that video, so it looks that the script isn't fully compatible with Firefox.

• http://www.youtube.com/watch?v=cdgQpa1pUUE&html5=1

Same problem and has caused BSOD when trying to load.

Tried extending the time FF will wait for script to load as well and just causes browser to freeze.

mazurkfsflip's fix worked

This is definitely not a Firefox 14+ problem! I had the same "Unresponsive script" popup with the YT HTML5 player using Firefox 11.0 on Ubuntu (10.10). I guess YouTube did some "upgrade" that didn't go quite well. Probably somebody missed to run a few unit tests or failed to submit the new code to QA for an UAT before deploying it to production ... :-(

So far the only workaround I've found is to leave the HTML5 trial on the YT page (http://www.youtube.com/html5/) and use the flash video player. :-(

The HTML5 player works with Chrome v20.0.1132.43 though ... I guess they did test only on Chrome. :-(

P.S.: I did test this with a completely new+clean Firefox profile (created a new profile, visited the YT HTML5 trial opt-in page and enabled the HTML5 player, then visited a YouTube video with the HTML5 player and got the "Unresponsive script" error/popup). And on the same computer with the same installed plugins (+versions) this worked without a problem just a few days ago (I guess the problem started occuring sometime yesterday or maybe the day before that ... I'm not quite sure).

mazurkfsflip is correct. Its an HTML5 youtube - firefox incompatibility. Go to the link in his post to opt out of the HTML5 trial and problem solved (for now).

In order to fix this problem go on the HTML5 page ( http://www.youtube.com/html5 ) at the bottom of the page, you will see "You are currently in the HTML5 trial." and "Leave the HTML5 Trial". Click on the second option and you will get rid of this error.

Thanks for the tip, it worked. However, clicking on the link you left gave a 404 error, but going to youtube and typing the html5 part worked. :)

for the record, as of this moment, the error says "Script: http://s.ytimg.com/yt/jsbin/html5player-vflGWJljH.js:53", 5 lines back

Thanks a lot! I thought it was a flash 11.3 error, but realized it was not after I had uninstalled the flash player and was still able to view videos (after waiting for the script to load, 20 seconds or so) on youtube. And thanks a lot Google for opting us in for something we didn't want to opt in for! Sleazy bastards.

If you don't have Flash installed then YouTube will use HTML5 player if your browser supports it. It didn't try to sneak anything in, just trying to help.

Guys, Chrome has absolutely no problems with the same pages on HTML5 youtube.Disabling HTML5 is a temporary solution, but this just puts us back to the other ugly situation where Firefox crushes and burns on every second flash video. It seems to me that this is a problem Mozilla has to deal with.

Well, other browsers also have problems. YouTube broke this and (as far as I know) they're working on it to fix this. This problem has nothing to do with the update to Firefox 14.0.1, it's also broken in Firefox 13 (I checked).

Youtube and everything was working fine until this afternoon. Trying to play YouTube just gets error messages about unresponsive scripts, and the browser locks up.

I got out of the HTML5 trials. When they get rid of the bugs and make it worth using, they can let me know.

Unfortunately Firefox and Flash 11.3 may have some issues and some may be trying HTML5 because of FlashPlayer issues.

Google know about the issue, and they should be updating the website later today.

What a ridiculous thing to have done to a great sum of people...jeez Google?!?!

I tell you what...I'll let you know if I want to be in a Beta...

Looks like Google/YouTube fixed the problem.