title: firefox-43.0.1 youtube - An error occurred. Please try again later
body: <p>I have upgaraded today my firefox to version    </p>
  
  <p>firefox-43.0.1.tar.bz2 (64 bit)</p>
  
  <p>Now i am seeing something wired. If i try to play the youtube videos then that does not work ( An error occurred. Please try again later ). If i start the firefox with the switch "-P"
  and create a new profile then all works. Since i wanted to make my current profile work, i disabled all extentions and tried again. But that did not help. Then i enabled only the user agent switcher and live http headers addon. I notice that if i change the user agent from the default firefox to google chrome then all work as expected, but i can not understand why is the default user agent not working then?</p>
  
  <p>Here is the default user agent http GET  to youtube. </p>
  
  <pre><code>GET / HTTP/1.1
  Host: youtube.com
  User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:43.0) Gecko/20100101 Firefox/43.0
  Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
  Accept-Language: en-US,en;q=0.5
  Accept-Encoding: gzip, deflate
  DNT: 1
  Connection: keep-alive
  </code></pre>
  
  <p>Here is the modified user agent http GET  to google. </p>
  
  <pre><code>GET / HTTP/1.1
  Host: youtube.com
  User-Agent: Mozilla/5.0 (X11; Linux i686 (x86_64)) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.130 Safari/537.36
  Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
  Accept-Language: en-US,en;q=0.5
  Accept-Encoding: gzip, deflate
  DNT: 1
  Connection: keep-alive
  </code></pre>
  
  <p>That was always working with the default user agent. If i go to the html5 test page on youtube i see that all elements are enabled i.e.</p>
  
  <p>HTMLVideoElement
  H.264
  WebM VP8 
  Media Source Extensions
  MSE &amp; H.264
  MSE &amp; WebM VP9</p>
  
  <p>So what i am missing here? Is there any particular string i should be looking in about:config?</p>
  
  <p>PS: Cache, cookies are cleared anytime i restart firefox.</p>