title: AJAX request is not sent before previous request is not finished
body: <p>I'm seeing strange behaviour with AJAX request being stuck before the previous request (not AJAX) is finished.</p>
  
  <p>I have a web page where video using HTML5  is playing and during that I want to make an AJAX request to the server. </p>
  
  <p>Below is some details of my case.
  Here is how it looks when request is stuck. First one is the video, second one is the AJAX which I want to send and it doesn't go anywhere before 1st is completed.
  <a href="https://i.stack.imgur.com/RC59v.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RC59v.png" alt="enter image description here"></a></p>
  
  <p>As soon as 1st is completed the 2nd one is done immediately.
  <a href="https://i.stack.imgur.com/DMBeU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DMBeU.png" alt="enter image description here"></a></p>
  
  <p>Ajax request is sent using just normal jQuery's $.ajax() call. </p>
  
  <p>Here is the request and response information for the video request that blocks AJAX request.</p>
  
  <pre><code>Request GET /portal/portlet/index/id/671/call/proxyVideo?entityId=1 HTTP/1.1
  Accept  */*
  If-Unmodified-Since Fri, 24 Apr 2015 08:18:29 GMT
  If-Match    "f91b54d-514740a87ff40"
  Range   bytes=360448-261207372
  User-Agent  Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko
  Referer http://mm.mac/content
  GetContentFeatures.DLNA.ORG 1
  Pragma  getIfoFileURI.dlna.org
  Accept-Language en-US
  Accept-Encoding gzip, deflate
  Host    mm.mac
  Connection  Keep-Alive
  Cache-Control   no-cache
  Cookie  PHPSESSID=41821op72k2s24mfrsbn5gad64
  
  
  Response    HTTP/1.1 206 Partial Content
  Date    Tue, 01 Dec 2015 13:39:31 GMT
  Server  Apache/2.4.16 (Unix) PHP/5.6.13
  X-Powered-By    PHP/5.6.13
  Expires Thu, 19 Nov 1981 08:52:00 GMT
  Cache-Control   no-store, no-cache, must-revalidate, post-check=0, pre-check=0
  Pragma  no-cache
  Last-Modified   Fri, 24 Apr 2015 08:18:29 GMT
  ETag    "f91b54d-514740a87ff40"
  Accept-Ranges   bytes
  Content-Length  260846925
  Access-Control-Allow-Methods    GET
  Content-Range   bytes 360448-261207372/261207373
  Keep-Alive  timeout=5, max=100
  Connection  Keep-Alive
  Content-Type    video/mp4
  </code></pre>
  
  <p>My question is why the AJAX request is blocked and how can I make it work?</p>
  
  <p>PS: Console doesn't report any errors or warnings.</p>