从请求cookie的服务器请求mp4文件

So I have a video tag

<video controls> 
     <source src="http://somewebsite/file.mp4" type="video/mp4" /> 
</video>

The server from http://somewebsite/file.mp4 checks if the request headers have a specific cookie, else you get 403 forbidden.

How can I send that cookie? I tried curl proxy, but there are problems with seeking. Maybe a flash based player that can do requests to media with specific http headers, or another way? Please help!