are Range requests for dynamic content supported?

[Ensiferous]

Your backend is responsible for returning the proper data, it can't
return the entire data and then expect nginx to send only part of it.

What you should actually do, if at all possible, is to use the
x-accel-redirect to direct nginx to the content location so that it can
read the file itself instead of getting it from your backend.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,225952,225956#msg-225956