Youtube - "Oops, your web browser is no longer supported"

Starting this morning when I go to youtube.com with Firefox 20.0 I get:

"Oops, your web browser is no longer supported"

Any idea what is causing this? I can still access the site, but I'd rather not be greeted with this message.

 

Do you fake the referer?
Mrk

 

No, I Haven't changed the referer (user agent, right?). I use Ghostery and HTTPS Everywhere - I don't know if they are factors, but I've been using them all along and until now I didn't have a problem. I don't know if some change in FF20 is the cause....?

 

It could just be Youtube screwing up again. I'm on the same version of FF and haven't seen this issue.

 

I tested it yesterday with FF 20.0 and seems to be ok.

 

I discovered that the problem was being caused by a plugin called CSFire. It's supposed to protect against cross-scripting attacks, but it was causing some strange interference. The browser is working normally now

 

You can replace the conflicting addon with NoScript. NS doesn't mess up Youtube and even if you decide to allow scripts globally, it will protect against Cross site scripting. I am a heavy Youtube user, never experience problems from NS/Flash/Firefox/SBIE when watching videos.

http://noscript.net/features#xss

Bo