Use Nginx built in secure link module the link you provided is being generated and served by PHP. ".com/vfm-admin/vfm-downloader.php?q="
Nginx's secure link module will resume downloads and support pseudo streaming etc but you will find it is PHP that does not.
Change your setup and modify your PHP code to not push the download through PHP but generate a link with a salted hash sum that Nginx may use.
http://nginx.org/en/docs/http/ngx_http_secure_link_module.html
http://www.networkflare.com/